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Catch pinch-zoom in browser
2019 Community Moderator ElectionHow do you disable browser Autocomplete on web form field / input tag?How to align checkboxes and their labels consistently cross-browsersHow to make a div 100% height of the browser window?Manual Pinch-Zoom event handling on iOS Safari after event.preventDefault();Pinch to zoom on canvasJavascript support for touch without blocking browsers pinch supportAdding pinch zoom to a UICollectionViewChrome on surface tablet disable sweep after pinch zoomCanvas shift while performing Pinch-zoom and Panning on Zoomed CanvasHammer.js: How to maintain one finger for window scroll, two fingers for image pinch/zoom/pan, etc
0
I have a web application that is basically a canvas you can draw on. I'm handling the drawing - either by mouse or by single finger touch - and it's working well.
The canvas is larger than the screen, and I need to implement my own zooming mechanism (because I only want to zoom the canvas, not the entire screen). I've added a handler to the wheel event, and I process Control-Wheels properly. Now I need to handle pinch-zooms.
My canvas as a track-action: pinch-zoom CSS settings. This enables two finger swipes for scrolling, which is excellent. I want to let the browser handle pinch-zooms, too, but I want to handle the zooming logic myself (like I do with the mouse wheel).
Is there any way to catch the pinch-zoom event and override the zooming behavior?
I'm using Chrome on Android, but this technique should also work with Safari on iOS.
html touch gesture pinchzoom
asked Mar 7 at 11:02
zmbqzmbq
29.3k962126
This question has an open bounty worth +100
reputation from zmbq ending ending at 2019-03-17 06:30:15Z">in 3 days.
This question has not received enough attention.
add a comment |
0
I have a web application that is basically a canvas you can draw on. I'm handling the drawing - either by mouse or by single finger touch - and it's working well.
The canvas is larger than the screen, and I need to implement my own zooming mechanism (because I only want to zoom the canvas, not the entire screen). I've added a handler to the wheel event, and I process Control-Wheels properly. Now I need to handle pinch-zooms.
My canvas as a track-action: pinch-zoom CSS settings. This enables two finger swipes for scrolling, which is excellent. I want to let the browser handle pinch-zooms, too, but I want to handle the zooming logic myself (like I do with the mouse wheel).
Is there any way to catch the pinch-zoom event and override the zooming behavior?
I'm using Chrome on Android, but this technique should also work with Safari on iOS.
html touch gesture pinchzoom
asked Mar 7 at 11:02
zmbqzmbq
29.3k962126
This question has an open bounty worth +100
reputation from zmbq ending ending at 2019-03-17 06:30:15Z">in 3 days.
This question has not received enough attention.
add a comment |
0
0
0
I have a web application that is basically a canvas you can draw on. I'm handling the drawing - either by mouse or by single finger touch - and it's working well.
The canvas is larger than the screen, and I need to implement my own zooming mechanism (because I only want to zoom the canvas, not the entire screen). I've added a handler to the wheel event, and I process Control-Wheels properly. Now I need to handle pinch-zooms.
My canvas as a track-action: pinch-zoom CSS settings. This enables two finger swipes for scrolling, which is excellent. I want to let the browser handle pinch-zooms, too, but I want to handle the zooming logic myself (like I do with the mouse wheel).
Is there any way to catch the pinch-zoom event and override the zooming behavior?
I'm using Chrome on Android, but this technique should also work with Safari on iOS.
html touch gesture pinchzoom
asked Mar 7 at 11:02
zmbqzmbq
29.3k962126
I have a web application that is basically a canvas you can draw on. I'm handling the drawing - either by mouse or by single finger touch - and it's working well.
The canvas is larger than the screen, and I need to implement my own zooming mechanism (because I only want to zoom the canvas, not the entire screen). I've added a handler to the wheel event, and I process Control-Wheels properly. Now I need to handle pinch-zooms.
My canvas as a track-action: pinch-zoom CSS settings. This enables two finger swipes for scrolling, which is excellent. I want to let the browser handle pinch-zooms, too, but I want to handle the zooming logic myself (like I do with the mouse wheel).
Is there any way to catch the pinch-zoom event and override the zooming behavior?
I'm using Chrome on Android, but this technique should also work with Safari on iOS.
html touch gesture pinchzoom
html touch gesture pinchzoom
asked Mar 7 at 11:02
zmbqzmbq
29.3k962126
asked Mar 7 at 11:02
zmbqzmbq
29.3k962126
asked Mar 7 at 11:02
zmbqzmbq
29.3k962126
asked Mar 7 at 11:02
zmbqzmbq
29.3k962126
asked Mar 7 at 11:02
zmbqzmbq
29.3k962126
29.3k962126
This question has an open bounty worth +100
reputation from zmbq ending ending at 2019-03-17 06:30:15Z">in 3 days.
This question has not received enough attention.
This question has an open bounty worth +100
reputation from zmbq ending ending at 2019-03-17 06:30:15Z">in 3 days.
This question has not received enough attention.
add a comment |
add a comment |
1 Answer
1
active
oldest
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0
nice idea btw.
i found something worth your time on codepen. also i stripped it down a little and inserted as snippet below. let me know if it helps you.
additionally if you want to use library, you can try hammer.js or jgestures for pinch zooming gestures.
var image_x = 0, image_y = 0;
var zoom = 0.5;
var mouse_x = 0, mouse_y = 0, finger_dist = 0;
var source_image_obj = new Image();
source_image_obj.addEventListener('load', function ()
reset_settings();
, false); // Reset (x,y,zoom) when new image loads
function load_url()
source_image_obj.src = document.getElementById("theurl").value; // load the image
function update_canvas()
var mainCanvas = document.getElementById("mainCanvas");
var mainCanvasCTX = document.getElementById("mainCanvas").getContext("2d");
var canvas_w = mainCanvas.width, canvas_h = mainCanvas.height; // make things easier to read below
// Keep picture in bounds
if (image_x - (canvas_w * zoom / 2) > source_image_obj.width) image_x = source_image_obj.width + (canvas_w * zoom / 2);
if (image_y - (canvas_h * zoom / 2) > source_image_obj.height) image_y = source_image_obj.height + (canvas_h * zoom / 2);
if (image_x + (canvas_w * zoom / 2) < 0) image_x = 0 - (canvas_w * zoom / 2);
if (image_y + (canvas_h * zoom / 2) < 0) image_y = 0 - (canvas_h * zoom / 2);
// Draw the scaled image onto the canvas
mainCanvasCTX.clearRect(0, 0, canvas_w, canvas_h);
mainCanvasCTX.drawImage(source_image_obj, image_x - (canvas_w * zoom / 2), image_y - (canvas_h * zoom / 2), canvas_w * zoom, canvas_h * zoom, 0, 0, canvas_w, canvas_h);
function reset_settings()
image_x = source_image_obj.width / 2;
image_y = source_image_obj.height / 2;
zoom = 1;
update_canvas(); // Draw the image in its new position
document.addEventListener('wheel', function (e)
if (e.deltaY < 0)
zoom = zoom * 1.5;
else
zoom = zoom / 1.5;
update_canvas();
, false);
document.addEventListener('mousemove', function (e)
if (e.buttons > 0)
window.getSelection().empty();
image_x = image_x + zoom * (mouse_x - e.clientX);
image_y = image_y + zoom * (mouse_y - e.clientY);
mouse_x = e.clientX;
mouse_y = e.clientY; // Save for next time
update_canvas(); // draw the image in its new position
, false);
function get_distance(e)
var diffX = e.touches[0].clientX - e.touches[1].clientX;
var diffY = e.touches[0].clientY - e.touches[1].clientY;
return Math.sqrt(diffX * diffX + diffY * diffY); // Pythagorean theorem
document.addEventListener('touchstart', function (e)
if (e.touches.length > 1) // if multiple touches (pinch zooming)
finger_dist = get_distance(e); // Save current finger distance
// Else just moving around
mouse_x = e.touches[0].clientX; // Save finger position
mouse_y = e.touches[0].clientY; //
, false);
document.addEventListener('touchmove', function (e)
e.preventDefault(); // Stop the window from moving
if (e.touches.length > 1) // If pinch-zooming
var new_finger_dist = get_distance(e); // Get current distance between fingers
zoom = zoom * Math.abs(finger_dist / new_finger_dist); // Zoom is proportional to change
finger_dist = new_finger_dist; // Save current distance for next time
else // Else just moving around
image_x = image_x + (zoom * (mouse_x - e.touches[0].clientX)); // Move the image
image_y = image_y + (zoom * (mouse_y - e.touches[0].clientY)); //
mouse_x = e.touches[0].clientX; // Save finger position for next time
mouse_y = e.touches[0].clientY; //
update_canvas(); // draw the new position
, false);
document.addEventListener('touchend', function (e)
mouse_x = e.touches[0].clientX;
mouse_y = e.touches[0].clientY; // could be down to 1 finger, back to moving image
, false); *
margin: 0;
padding: 0;
box-sizing: border-box;
canvas
background: #e74c3c;
border: 4px solid black;
.box-photo
border: 1px dashed black;
.box-photo img
width: 100%;
<html>
<head>
<meta charset="utf-8" />
<body onload="load_url();">
<div class="box">
<div class="box-photo">
<canvas id="mainCanvas" width="500" height="600">
<input id="theurl" value="https://mlb-s1-p.mlstatic.com/relogio-mondaine-classico-78527-original-a-prova-dagua-202101-MLB20273713546_042015-F.jpg">
Your browser does not support the HTML5 canvas tag.
</canvas>
</div>
</div>
</body>
</html>answered 17 hours ago
GalzorGalzor
616
add a comment |
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1 Answer
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1 Answer
1
active
oldest
votes
active
oldest
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active
oldest
votes
0
nice idea btw.
i found something worth your time on codepen. also i stripped it down a little and inserted as snippet below. let me know if it helps you.
additionally if you want to use library, you can try hammer.js or jgestures for pinch zooming gestures.
var image_x = 0, image_y = 0;
var zoom = 0.5;
var mouse_x = 0, mouse_y = 0, finger_dist = 0;
var source_image_obj = new Image();
source_image_obj.addEventListener('load', function ()
reset_settings();
, false); // Reset (x,y,zoom) when new image loads
function load_url()
source_image_obj.src = document.getElementById("theurl").value; // load the image
function update_canvas()
var mainCanvas = document.getElementById("mainCanvas");
var mainCanvasCTX = document.getElementById("mainCanvas").getContext("2d");
var canvas_w = mainCanvas.width, canvas_h = mainCanvas.height; // make things easier to read below
// Keep picture in bounds
if (image_x - (canvas_w * zoom / 2) > source_image_obj.width) image_x = source_image_obj.width + (canvas_w * zoom / 2);
if (image_y - (canvas_h * zoom / 2) > source_image_obj.height) image_y = source_image_obj.height + (canvas_h * zoom / 2);
if (image_x + (canvas_w * zoom / 2) < 0) image_x = 0 - (canvas_w * zoom / 2);
if (image_y + (canvas_h * zoom / 2) < 0) image_y = 0 - (canvas_h * zoom / 2);
// Draw the scaled image onto the canvas
mainCanvasCTX.clearRect(0, 0, canvas_w, canvas_h);
mainCanvasCTX.drawImage(source_image_obj, image_x - (canvas_w * zoom / 2), image_y - (canvas_h * zoom / 2), canvas_w * zoom, canvas_h * zoom, 0, 0, canvas_w, canvas_h);
function reset_settings()
image_x = source_image_obj.width / 2;
image_y = source_image_obj.height / 2;
zoom = 1;
update_canvas(); // Draw the image in its new position
document.addEventListener('wheel', function (e)
if (e.deltaY < 0)
zoom = zoom * 1.5;
else
zoom = zoom / 1.5;
update_canvas();
, false);
document.addEventListener('mousemove', function (e)
if (e.buttons > 0)
window.getSelection().empty();
image_x = image_x + zoom * (mouse_x - e.clientX);
image_y = image_y + zoom * (mouse_y - e.clientY);
mouse_x = e.clientX;
mouse_y = e.clientY; // Save for next time
update_canvas(); // draw the image in its new position
, false);
function get_distance(e)
var diffX = e.touches[0].clientX - e.touches[1].clientX;
var diffY = e.touches[0].clientY - e.touches[1].clientY;
return Math.sqrt(diffX * diffX + diffY * diffY); // Pythagorean theorem
document.addEventListener('touchstart', function (e)
if (e.touches.length > 1) // if multiple touches (pinch zooming)
finger_dist = get_distance(e); // Save current finger distance
// Else just moving around
mouse_x = e.touches[0].clientX; // Save finger position
mouse_y = e.touches[0].clientY; //
, false);
document.addEventListener('touchmove', function (e)
e.preventDefault(); // Stop the window from moving
if (e.touches.length > 1) // If pinch-zooming
var new_finger_dist = get_distance(e); // Get current distance between fingers
zoom = zoom * Math.abs(finger_dist / new_finger_dist); // Zoom is proportional to change
finger_dist = new_finger_dist; // Save current distance for next time
else // Else just moving around
image_x = image_x + (zoom * (mouse_x - e.touches[0].clientX)); // Move the image
image_y = image_y + (zoom * (mouse_y - e.touches[0].clientY)); //
mouse_x = e.touches[0].clientX; // Save finger position for next time
mouse_y = e.touches[0].clientY; //
update_canvas(); // draw the new position
, false);
document.addEventListener('touchend', function (e)
mouse_x = e.touches[0].clientX;
mouse_y = e.touches[0].clientY; // could be down to 1 finger, back to moving image
, false); *
margin: 0;
padding: 0;
box-sizing: border-box;
canvas
background: #e74c3c;
border: 4px solid black;
.box-photo
border: 1px dashed black;
.box-photo img
width: 100%;
<html>
<head>
<meta charset="utf-8" />
<body onload="load_url();">
<div class="box">
<div class="box-photo">
<canvas id="mainCanvas" width="500" height="600">
<input id="theurl" value="https://mlb-s1-p.mlstatic.com/relogio-mondaine-classico-78527-original-a-prova-dagua-202101-MLB20273713546_042015-F.jpg">
Your browser does not support the HTML5 canvas tag.
</canvas>
</div>
</div>
</body>
</html>answered 17 hours ago
GalzorGalzor
616
add a comment |
0
nice idea btw.
i found something worth your time on codepen. also i stripped it down a little and inserted as snippet below. let me know if it helps you.
additionally if you want to use library, you can try hammer.js or jgestures for pinch zooming gestures.
var image_x = 0, image_y = 0;
var zoom = 0.5;
var mouse_x = 0, mouse_y = 0, finger_dist = 0;
var source_image_obj = new Image();
source_image_obj.addEventListener('load', function ()
reset_settings();
, false); // Reset (x,y,zoom) when new image loads
function load_url()
source_image_obj.src = document.getElementById("theurl").value; // load the image
function update_canvas()
var mainCanvas = document.getElementById("mainCanvas");
var mainCanvasCTX = document.getElementById("mainCanvas").getContext("2d");
var canvas_w = mainCanvas.width, canvas_h = mainCanvas.height; // make things easier to read below
// Keep picture in bounds
if (image_x - (canvas_w * zoom / 2) > source_image_obj.width) image_x = source_image_obj.width + (canvas_w * zoom / 2);
if (image_y - (canvas_h * zoom / 2) > source_image_obj.height) image_y = source_image_obj.height + (canvas_h * zoom / 2);
if (image_x + (canvas_w * zoom / 2) < 0) image_x = 0 - (canvas_w * zoom / 2);
if (image_y + (canvas_h * zoom / 2) < 0) image_y = 0 - (canvas_h * zoom / 2);
// Draw the scaled image onto the canvas
mainCanvasCTX.clearRect(0, 0, canvas_w, canvas_h);
mainCanvasCTX.drawImage(source_image_obj, image_x - (canvas_w * zoom / 2), image_y - (canvas_h * zoom / 2), canvas_w * zoom, canvas_h * zoom, 0, 0, canvas_w, canvas_h);
function reset_settings()
image_x = source_image_obj.width / 2;
image_y = source_image_obj.height / 2;
zoom = 1;
update_canvas(); // Draw the image in its new position
document.addEventListener('wheel', function (e)
if (e.deltaY < 0)
zoom = zoom * 1.5;
else
zoom = zoom / 1.5;
update_canvas();
, false);
document.addEventListener('mousemove', function (e)
if (e.buttons > 0)
window.getSelection().empty();
image_x = image_x + zoom * (mouse_x - e.clientX);
image_y = image_y + zoom * (mouse_y - e.clientY);
mouse_x = e.clientX;
mouse_y = e.clientY; // Save for next time
update_canvas(); // draw the image in its new position
, false);
function get_distance(e)
var diffX = e.touches[0].clientX - e.touches[1].clientX;
var diffY = e.touches[0].clientY - e.touches[1].clientY;
return Math.sqrt(diffX * diffX + diffY * diffY); // Pythagorean theorem
document.addEventListener('touchstart', function (e)
if (e.touches.length > 1) // if multiple touches (pinch zooming)
finger_dist = get_distance(e); // Save current finger distance
// Else just moving around
mouse_x = e.touches[0].clientX; // Save finger position
mouse_y = e.touches[0].clientY; //
, false);
document.addEventListener('touchmove', function (e)
e.preventDefault(); // Stop the window from moving
if (e.touches.length > 1) // If pinch-zooming
var new_finger_dist = get_distance(e); // Get current distance between fingers
zoom = zoom * Math.abs(finger_dist / new_finger_dist); // Zoom is proportional to change
finger_dist = new_finger_dist; // Save current distance for next time
else // Else just moving around
image_x = image_x + (zoom * (mouse_x - e.touches[0].clientX)); // Move the image
image_y = image_y + (zoom * (mouse_y - e.touches[0].clientY)); //
mouse_x = e.touches[0].clientX; // Save finger position for next time
mouse_y = e.touches[0].clientY; //
update_canvas(); // draw the new position
, false);
document.addEventListener('touchend', function (e)
mouse_x = e.touches[0].clientX;
mouse_y = e.touches[0].clientY; // could be down to 1 finger, back to moving image
, false); *
margin: 0;
padding: 0;
box-sizing: border-box;
canvas
background: #e74c3c;
border: 4px solid black;
.box-photo
border: 1px dashed black;
.box-photo img
width: 100%;
<html>
<head>
<meta charset="utf-8" />
<body onload="load_url();">
<div class="box">
<div class="box-photo">
<canvas id="mainCanvas" width="500" height="600">
<input id="theurl" value="https://mlb-s1-p.mlstatic.com/relogio-mondaine-classico-78527-original-a-prova-dagua-202101-MLB20273713546_042015-F.jpg">
Your browser does not support the HTML5 canvas tag.
</canvas>
</div>
</div>
</body>
</html>answered 17 hours ago
GalzorGalzor
616
add a comment |
0
0
0
nice idea btw.
i found something worth your time on codepen. also i stripped it down a little and inserted as snippet below. let me know if it helps you.
additionally if you want to use library, you can try hammer.js or jgestures for pinch zooming gestures.
var image_x = 0, image_y = 0;
var zoom = 0.5;
var mouse_x = 0, mouse_y = 0, finger_dist = 0;
var source_image_obj = new Image();
source_image_obj.addEventListener('load', function ()
reset_settings();
, false); // Reset (x,y,zoom) when new image loads
function load_url()
source_image_obj.src = document.getElementById("theurl").value; // load the image
function update_canvas()
var mainCanvas = document.getElementById("mainCanvas");
var mainCanvasCTX = document.getElementById("mainCanvas").getContext("2d");
var canvas_w = mainCanvas.width, canvas_h = mainCanvas.height; // make things easier to read below
// Keep picture in bounds
if (image_x - (canvas_w * zoom / 2) > source_image_obj.width) image_x = source_image_obj.width + (canvas_w * zoom / 2);
if (image_y - (canvas_h * zoom / 2) > source_image_obj.height) image_y = source_image_obj.height + (canvas_h * zoom / 2);
if (image_x + (canvas_w * zoom / 2) < 0) image_x = 0 - (canvas_w * zoom / 2);
if (image_y + (canvas_h * zoom / 2) < 0) image_y = 0 - (canvas_h * zoom / 2);
// Draw the scaled image onto the canvas
mainCanvasCTX.clearRect(0, 0, canvas_w, canvas_h);
mainCanvasCTX.drawImage(source_image_obj, image_x - (canvas_w * zoom / 2), image_y - (canvas_h * zoom / 2), canvas_w * zoom, canvas_h * zoom, 0, 0, canvas_w, canvas_h);
function reset_settings()
image_x = source_image_obj.width / 2;
image_y = source_image_obj.height / 2;
zoom = 1;
update_canvas(); // Draw the image in its new position
document.addEventListener('wheel', function (e)
if (e.deltaY < 0)
zoom = zoom * 1.5;
else
zoom = zoom / 1.5;
update_canvas();
, false);
document.addEventListener('mousemove', function (e)
if (e.buttons > 0)
window.getSelection().empty();
image_x = image_x + zoom * (mouse_x - e.clientX);
image_y = image_y + zoom * (mouse_y - e.clientY);
mouse_x = e.clientX;
mouse_y = e.clientY; // Save for next time
update_canvas(); // draw the image in its new position
, false);
function get_distance(e)
var diffX = e.touches[0].clientX - e.touches[1].clientX;
var diffY = e.touches[0].clientY - e.touches[1].clientY;
return Math.sqrt(diffX * diffX + diffY * diffY); // Pythagorean theorem
document.addEventListener('touchstart', function (e)
if (e.touches.length > 1) // if multiple touches (pinch zooming)
finger_dist = get_distance(e); // Save current finger distance
// Else just moving around
mouse_x = e.touches[0].clientX; // Save finger position
mouse_y = e.touches[0].clientY; //
, false);
document.addEventListener('touchmove', function (e)
e.preventDefault(); // Stop the window from moving
if (e.touches.length > 1) // If pinch-zooming
var new_finger_dist = get_distance(e); // Get current distance between fingers
zoom = zoom * Math.abs(finger_dist / new_finger_dist); // Zoom is proportional to change
finger_dist = new_finger_dist; // Save current distance for next time
else // Else just moving around
image_x = image_x + (zoom * (mouse_x - e.touches[0].clientX)); // Move the image
image_y = image_y + (zoom * (mouse_y - e.touches[0].clientY)); //
mouse_x = e.touches[0].clientX; // Save finger position for next time
mouse_y = e.touches[0].clientY; //
update_canvas(); // draw the new position
, false);
document.addEventListener('touchend', function (e)
mouse_x = e.touches[0].clientX;
mouse_y = e.touches[0].clientY; // could be down to 1 finger, back to moving image
, false); *
margin: 0;
padding: 0;
box-sizing: border-box;
canvas
background: #e74c3c;
border: 4px solid black;
.box-photo
border: 1px dashed black;
.box-photo img
width: 100%;
<html>
<head>
<meta charset="utf-8" />
<body onload="load_url();">
<div class="box">
<div class="box-photo">
<canvas id="mainCanvas" width="500" height="600">
<input id="theurl" value="https://mlb-s1-p.mlstatic.com/relogio-mondaine-classico-78527-original-a-prova-dagua-202101-MLB20273713546_042015-F.jpg">
Your browser does not support the HTML5 canvas tag.
</canvas>
</div>
</div>
</body>
</html>answered 17 hours ago
GalzorGalzor
616
nice idea btw.
i found something worth your time on codepen. also i stripped it down a little and inserted as snippet below. let me know if it helps you.
additionally if you want to use library, you can try hammer.js or jgestures for pinch zooming gestures.
var image_x = 0, image_y = 0;
var zoom = 0.5;
var mouse_x = 0, mouse_y = 0, finger_dist = 0;
var source_image_obj = new Image();
source_image_obj.addEventListener('load', function ()
reset_settings();
, false); // Reset (x,y,zoom) when new image loads
function load_url()
source_image_obj.src = document.getElementById("theurl").value; // load the image
function update_canvas()
var mainCanvas = document.getElementById("mainCanvas");
var mainCanvasCTX = document.getElementById("mainCanvas").getContext("2d");
var canvas_w = mainCanvas.width, canvas_h = mainCanvas.height; // make things easier to read below
// Keep picture in bounds
if (image_x - (canvas_w * zoom / 2) > source_image_obj.width) image_x = source_image_obj.width + (canvas_w * zoom / 2);
if (image_y - (canvas_h * zoom / 2) > source_image_obj.height) image_y = source_image_obj.height + (canvas_h * zoom / 2);
if (image_x + (canvas_w * zoom / 2) < 0) image_x = 0 - (canvas_w * zoom / 2);
if (image_y + (canvas_h * zoom / 2) < 0) image_y = 0 - (canvas_h * zoom / 2);
// Draw the scaled image onto the canvas
mainCanvasCTX.clearRect(0, 0, canvas_w, canvas_h);
mainCanvasCTX.drawImage(source_image_obj, image_x - (canvas_w * zoom / 2), image_y - (canvas_h * zoom / 2), canvas_w * zoom, canvas_h * zoom, 0, 0, canvas_w, canvas_h);
function reset_settings()
image_x = source_image_obj.width / 2;
image_y = source_image_obj.height / 2;
zoom = 1;
update_canvas(); // Draw the image in its new position
document.addEventListener('wheel', function (e)
if (e.deltaY < 0)
zoom = zoom * 1.5;
else
zoom = zoom / 1.5;
update_canvas();
, false);
document.addEventListener('mousemove', function (e)
if (e.buttons > 0)
window.getSelection().empty();
image_x = image_x + zoom * (mouse_x - e.clientX);
image_y = image_y + zoom * (mouse_y - e.clientY);
mouse_x = e.clientX;
mouse_y = e.clientY; // Save for next time
update_canvas(); // draw the image in its new position
, false);
function get_distance(e)
var diffX = e.touches[0].clientX - e.touches[1].clientX;
var diffY = e.touches[0].clientY - e.touches[1].clientY;
return Math.sqrt(diffX * diffX + diffY * diffY); // Pythagorean theorem
document.addEventListener('touchstart', function (e)
if (e.touches.length > 1) // if multiple touches (pinch zooming)
finger_dist = get_distance(e); // Save current finger distance
// Else just moving around
mouse_x = e.touches[0].clientX; // Save finger position
mouse_y = e.touches[0].clientY; //
, false);
document.addEventListener('touchmove', function (e)
e.preventDefault(); // Stop the window from moving
if (e.touches.length > 1) // If pinch-zooming
var new_finger_dist = get_distance(e); // Get current distance between fingers
zoom = zoom * Math.abs(finger_dist / new_finger_dist); // Zoom is proportional to change
finger_dist = new_finger_dist; // Save current distance for next time
else // Else just moving around
image_x = image_x + (zoom * (mouse_x - e.touches[0].clientX)); // Move the image
image_y = image_y + (zoom * (mouse_y - e.touches[0].clientY)); //
mouse_x = e.touches[0].clientX; // Save finger position for next time
mouse_y = e.touches[0].clientY; //
update_canvas(); // draw the new position
, false);
document.addEventListener('touchend', function (e)
mouse_x = e.touches[0].clientX;
mouse_y = e.touches[0].clientY; // could be down to 1 finger, back to moving image
, false); *
margin: 0;
padding: 0;
box-sizing: border-box;
canvas
background: #e74c3c;
border: 4px solid black;
.box-photo
border: 1px dashed black;
.box-photo img
width: 100%;
<html>
<head>
<meta charset="utf-8" />
<body onload="load_url();">
<div class="box">
<div class="box-photo">
<canvas id="mainCanvas" width="500" height="600">
<input id="theurl" value="https://mlb-s1-p.mlstatic.com/relogio-mondaine-classico-78527-original-a-prova-dagua-202101-MLB20273713546_042015-F.jpg">
Your browser does not support the HTML5 canvas tag.
</canvas>
</div>
</div>
</body>
</html> var image_x = 0, image_y = 0;
var zoom = 0.5;
var mouse_x = 0, mouse_y = 0, finger_dist = 0;
var source_image_obj = new Image();
source_image_obj.addEventListener('load', function ()
reset_settings();
, false); // Reset (x,y,zoom) when new image loads
function load_url()
source_image_obj.src = document.getElementById("theurl").value; // load the image
function update_canvas()
var mainCanvas = document.getElementById("mainCanvas");
var mainCanvasCTX = document.getElementById("mainCanvas").getContext("2d");
var canvas_w = mainCanvas.width, canvas_h = mainCanvas.height; // make things easier to read below
// Keep picture in bounds
if (image_x - (canvas_w * zoom / 2) > source_image_obj.width) image_x = source_image_obj.width + (canvas_w * zoom / 2);
if (image_y - (canvas_h * zoom / 2) > source_image_obj.height) image_y = source_image_obj.height + (canvas_h * zoom / 2);
if (image_x + (canvas_w * zoom / 2) < 0) image_x = 0 - (canvas_w * zoom / 2);
if (image_y + (canvas_h * zoom / 2) < 0) image_y = 0 - (canvas_h * zoom / 2);
// Draw the scaled image onto the canvas
mainCanvasCTX.clearRect(0, 0, canvas_w, canvas_h);
mainCanvasCTX.drawImage(source_image_obj, image_x - (canvas_w * zoom / 2), image_y - (canvas_h * zoom / 2), canvas_w * zoom, canvas_h * zoom, 0, 0, canvas_w, canvas_h);
function reset_settings()
image_x = source_image_obj.width / 2;
image_y = source_image_obj.height / 2;
zoom = 1;
update_canvas(); // Draw the image in its new position
document.addEventListener('wheel', function (e)
if (e.deltaY < 0)
zoom = zoom * 1.5;
else
zoom = zoom / 1.5;
update_canvas();
, false);
document.addEventListener('mousemove', function (e)
if (e.buttons > 0)
window.getSelection().empty();
image_x = image_x + zoom * (mouse_x - e.clientX);
image_y = image_y + zoom * (mouse_y - e.clientY);
mouse_x = e.clientX;
mouse_y = e.clientY; // Save for next time
update_canvas(); // draw the image in its new position
, false);
function get_distance(e)
var diffX = e.touches[0].clientX - e.touches[1].clientX;
var diffY = e.touches[0].clientY - e.touches[1].clientY;
return Math.sqrt(diffX * diffX + diffY * diffY); // Pythagorean theorem
document.addEventListener('touchstart', function (e)
if (e.touches.length > 1) // if multiple touches (pinch zooming)
finger_dist = get_distance(e); // Save current finger distance
// Else just moving around
mouse_x = e.touches[0].clientX; // Save finger position
mouse_y = e.touches[0].clientY; //
, false);
document.addEventListener('touchmove', function (e)
e.preventDefault(); // Stop the window from moving
if (e.touches.length > 1) // If pinch-zooming
var new_finger_dist = get_distance(e); // Get current distance between fingers
zoom = zoom * Math.abs(finger_dist / new_finger_dist); // Zoom is proportional to change
finger_dist = new_finger_dist; // Save current distance for next time
else // Else just moving around
image_x = image_x + (zoom * (mouse_x - e.touches[0].clientX)); // Move the image
image_y = image_y + (zoom * (mouse_y - e.touches[0].clientY)); //
mouse_x = e.touches[0].clientX; // Save finger position for next time
mouse_y = e.touches[0].clientY; //
update_canvas(); // draw the new position
, false);
document.addEventListener('touchend', function (e)
mouse_x = e.touches[0].clientX;
mouse_y = e.touches[0].clientY; // could be down to 1 finger, back to moving image
, false); *
margin: 0;
padding: 0;
box-sizing: border-box;
canvas
background: #e74c3c;
border: 4px solid black;
.box-photo
border: 1px dashed black;
.box-photo img
width: 100%;
<html>
<head>
<meta charset="utf-8" />
<body onload="load_url();">
<div class="box">
<div class="box-photo">
<canvas id="mainCanvas" width="500" height="600">
<input id="theurl" value="https://mlb-s1-p.mlstatic.com/relogio-mondaine-classico-78527-original-a-prova-dagua-202101-MLB20273713546_042015-F.jpg">
Your browser does not support the HTML5 canvas tag.
</canvas>
</div>
</div>
</body>
</html> var image_x = 0, image_y = 0;
var zoom = 0.5;
var mouse_x = 0, mouse_y = 0, finger_dist = 0;
var source_image_obj = new Image();
source_image_obj.addEventListener('load', function ()
reset_settings();
, false); // Reset (x,y,zoom) when new image loads
function load_url()
source_image_obj.src = document.getElementById("theurl").value; // load the image
function update_canvas()
var mainCanvas = document.getElementById("mainCanvas");
var mainCanvasCTX = document.getElementById("mainCanvas").getContext("2d");
var canvas_w = mainCanvas.width, canvas_h = mainCanvas.height; // make things easier to read below
// Keep picture in bounds
if (image_x - (canvas_w * zoom / 2) > source_image_obj.width) image_x = source_image_obj.width + (canvas_w * zoom / 2);
if (image_y - (canvas_h * zoom / 2) > source_image_obj.height) image_y = source_image_obj.height + (canvas_h * zoom / 2);
if (image_x + (canvas_w * zoom / 2) < 0) image_x = 0 - (canvas_w * zoom / 2);
if (image_y + (canvas_h * zoom / 2) < 0) image_y = 0 - (canvas_h * zoom / 2);
// Draw the scaled image onto the canvas
mainCanvasCTX.clearRect(0, 0, canvas_w, canvas_h);
mainCanvasCTX.drawImage(source_image_obj, image_x - (canvas_w * zoom / 2), image_y - (canvas_h * zoom / 2), canvas_w * zoom, canvas_h * zoom, 0, 0, canvas_w, canvas_h);
function reset_settings()
image_x = source_image_obj.width / 2;
image_y = source_image_obj.height / 2;
zoom = 1;
update_canvas(); // Draw the image in its new position
document.addEventListener('wheel', function (e)
if (e.deltaY < 0)
zoom = zoom * 1.5;
else
zoom = zoom / 1.5;
update_canvas();
, false);
document.addEventListener('mousemove', function (e)
if (e.buttons > 0)
window.getSelection().empty();
image_x = image_x + zoom * (mouse_x - e.clientX);
image_y = image_y + zoom * (mouse_y - e.clientY);
mouse_x = e.clientX;
mouse_y = e.clientY; // Save for next time
update_canvas(); // draw the image in its new position
, false);
function get_distance(e)
var diffX = e.touches[0].clientX - e.touches[1].clientX;
var diffY = e.touches[0].clientY - e.touches[1].clientY;
return Math.sqrt(diffX * diffX + diffY * diffY); // Pythagorean theorem
document.addEventListener('touchstart', function (e)
if (e.touches.length > 1) // if multiple touches (pinch zooming)
finger_dist = get_distance(e); // Save current finger distance
// Else just moving around
mouse_x = e.touches[0].clientX; // Save finger position
mouse_y = e.touches[0].clientY; //
, false);
document.addEventListener('touchmove', function (e)
e.preventDefault(); // Stop the window from moving
if (e.touches.length > 1) // If pinch-zooming
var new_finger_dist = get_distance(e); // Get current distance between fingers
zoom = zoom * Math.abs(finger_dist / new_finger_dist); // Zoom is proportional to change
finger_dist = new_finger_dist; // Save current distance for next time
else // Else just moving around
image_x = image_x + (zoom * (mouse_x - e.touches[0].clientX)); // Move the image
image_y = image_y + (zoom * (mouse_y - e.touches[0].clientY)); //
mouse_x = e.touches[0].clientX; // Save finger position for next time
mouse_y = e.touches[0].clientY; //
update_canvas(); // draw the new position
, false);
document.addEventListener('touchend', function (e)
mouse_x = e.touches[0].clientX;
mouse_y = e.touches[0].clientY; // could be down to 1 finger, back to moving image
, false); *
margin: 0;
padding: 0;
box-sizing: border-box;
canvas
background: #e74c3c;
border: 4px solid black;
.box-photo
border: 1px dashed black;
.box-photo img
width: 100%;
<html>
<head>
<meta charset="utf-8" />
<body onload="load_url();">
<div class="box">
<div class="box-photo">
<canvas id="mainCanvas" width="500" height="600">
<input id="theurl" value="https://mlb-s1-p.mlstatic.com/relogio-mondaine-classico-78527-original-a-prova-dagua-202101-MLB20273713546_042015-F.jpg">
Your browser does not support the HTML5 canvas tag.
</canvas>
</div>
</div>
</body>
</html>answered 17 hours ago
GalzorGalzor
616
answered 17 hours ago
GalzorGalzor
616
answered 17 hours ago
GalzorGalzor
616
answered 17 hours ago
GalzorGalzor
616
616
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