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LinearGradient support absolute offset #637

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LinearGradient support absolute offset #637

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9a41093
Support absolute offset
shiftonetothree Sep 15, 2020
d1e8955
Fix title
shiftonetothree Sep 15, 2020
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40 changes: 39 additions & 1 deletion src/graphic/Style.js
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,44 @@ function createLinearGradient(ctx, obj, rect) {
return canvasGradient;
}

function transformAbsoluteOffset(offset, absolute, obj, rect) {
var x = obj.x == null ? 0 : obj.x;
var x2 = obj.x2 == null ? 1 : obj.x2;
var y = obj.y == null ? 0 : obj.y;
var y2 = obj.y2 == null ? 0 : obj.y2;

if (!obj.global) {
x = x * rect.width + rect.x;
x2 = x2 * rect.width + rect.x;
y = y * rect.height + rect.y;
y2 = y2 * rect.height + rect.y;
}

// Fix NaN when rect is Infinity
x = isNaN(x) ? 0 : x;
x2 = isNaN(x2) ? 1 : x2;
y = isNaN(y) ? 0 : y;
y2 = isNaN(y2) ? 0 : y2;
var length = Math.sqrt(Math.pow(x2 - x, 2) + Math.pow(y2 - y, 2));

if (absolute === 'start' | absolute === 'end') {
if (length === 0) {
return 0;
}
if (isFinite(offset)) {
if (absolute === 'start') {
return Math.min(Math.max(offset / length, 0), 1);
}
else if (absolute === 'end') {
return Math.min(Math.max((length - offset) / length, 0), 1);
}
throw new Error('absolute must to be \'start\' or \'end\'' + offset);
}
throw new Error('offset need to be finite:' + offset);
}
return offset;
}

function createRadialGradient(ctx, obj, rect) {
var width = rect.width;
var height = rect.height;
Expand Down Expand Up @@ -477,7 +515,7 @@ Style.prototype = {
var colorStops = obj.colorStops;
for (var i = 0; i < colorStops.length; i++) {
canvasGradient.addColorStop(
colorStops[i].offset, colorStops[i].color
transformAbsoluteOffset(colorStops[i].offset, colorStops[i].absolute, obj, rect), colorStops[i].color
);
}
return canvasGradient;
Expand Down
58 changes: 58 additions & 0 deletions test/barGradient.html
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Original file line number Diff line number Diff line change
@@ -0,0 +1,58 @@
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Bar Gradient</title>
<script src="../dist/zrender.js"></script>
<meta name="viewport" content="width=device-width, initial-scale=1" />
</head>
<body>
<script type="text/javascript">
var N = 50;
for (var k = 0; k < 50; k++) {
var div = document.createElement('div');
var width = 600;
var height = 300;
div.style.width = width + 'px';
div.style.height = height + 'px';
document.body.appendChild(div);
// 初始化zrender
var zr = zrender.init(div, {
renderer: 'canvas'
});

for (var i = 0; i < N; i++) {
var h = height * Math.random();
var barShape = new zrender.Rect({
shape: {
x: i * width / N,
y: height,
width: width / N,
height: 0
},
style: {
fill: new zrender.LinearGradient(0,0,0,1,[
{offset:0,color:"red"},
{offset:2,color:"red",absolute:"start"},
{offset:2,color:"transparent",absolute:"start"},
{offset:4,color:"transparent",absolute:"start"},
{offset:4,color:"blue",absolute:"start"},
{offset:2,color:"blue",absolute:"end"},
{offset:2,color:"green",absolute:"end"},
{offset:1,color:"green"}
])
},
});
zr.add(barShape);

barShape.animateTo({
shape: {
height: h,
y: height - h
}
}, 500);
}
}
</script>
</body>
</html>