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Restore context opacity after drawing layers

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Closes #2455
This commit is contained in:
Frederic Junod
2014-08-05 14:59:32 +02:00
parent 1bd522d96f
commit ae98ee8b4a
1 changed files with 5 additions and 0 deletions
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5
src/ol/renderer/canvas/canvaslayerrenderer.js
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@@ -45,6 +45,10 @@ ol.renderer.canvas.Layer.prototype.composeFrame =
var image = this.getImage(); var image = this.getImage();
if (!goog.isNull(image)) { if (!goog.isNull(image)) {
var imageTransform = this.getImageTransform(); var imageTransform = this.getImageTransform();
// for performance reasons, context.save / context.restore is not used
// to save and restore the transformation matrix and the opacity.
// see http://jsperf.com/context-save-restore-versus-variable
var alpha = context.globalAlpha;
context.globalAlpha = layerState.opacity; context.globalAlpha = layerState.opacity;
// for performance reasons, context.setTransform is only used // for performance reasons, context.setTransform is only used
@@ -67,6 +71,7 @@ ol.renderer.canvas.Layer.prototype.composeFrame =
context.drawImage(image, 0, 0); context.drawImage(image, 0, 0);
context.setTransform(1, 0, 0, 1, 0, 0); context.setTransform(1, 0, 0, 1, 0, 0);
} }
context.globalAlpha = alpha;
} }
this.dispatchPostComposeEvent(context, frameState); this.dispatchPostComposeEvent(context, frameState);