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Handle slow loading of images 

Internet Explorer seems to flag images as loaded prematurely, which
can result in rendering bugs. We can detect this by looking at the
dimensions though.
This commit is contained in:
Pierre Ossman 2019-12-23 15:40:17 +01:00
parent 4babdf33bd
commit c4eb4ddcfe
2 changed files with 32 additions and 4 deletions
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9
core/display.js
View File

@ -360,8 +360,14 @@ export default class Display {
}
imageRect(x, y, width, height, mime, arr) {
/* The internal logic cannot handle empty images, so bail early */
if ((width === 0) || (height === 0)) {
return;
}
const img = new Image();
img.src = "data: " + mime + ";base64," + Base64.encode(arr);
this._renderQ_push({
'type': 'img',
'img': img,
@ -617,7 +623,8 @@ export default class Display {
this.blitRgbxImage(a.x, a.y, a.width, a.height, a.data, 0, true);
break;
case 'img':
if (a.img.complete) {
/* IE tends to set "complete" prematurely, so check dimensions */
if (a.img.complete && (a.img.width !== 0) && (a.img.height !== 0)) {
if (a.img.width !== a.width || a.img.height !== a.height) {
Log.Error("Decoded image has incorrect dimensions. Got " +
a.img.width + "x" + a.img.height + ". Expected " +

27
tests/test.display.js
View File

@ -300,7 +300,7 @@ describe('Display/Canvas Helper', function () {
});
it('should support drawing images via #imageRect', function (done) {
display.imageRect(0, 0, "image/png", make_image_png(checked_data));
display.imageRect(0, 0, 4, 4, "image/png", make_image_png(checked_data));
display.flip();
display.onflush = () => {
expect(display).to.have.displayed(checked_data);
@ -401,8 +401,8 @@ describe('Display/Canvas Helper', function () {
});
it('should wait until an image is loaded to attempt to draw it and the rest of the queue', function () {
const img = { complete: false, addEventListener: sinon.spy() };
display._renderQ = [{ type: 'img', x: 3, y: 4, img: img },
const img = { complete: false, width: 4, height: 4, addEventListener: sinon.spy() };
display._renderQ = [{ type: 'img', x: 3, y: 4, width: 4, height: 4, img: img },
{ type: 'fill', x: 1, y: 2, width: 3, height: 4, color: 5 }];
display.drawImage = sinon.spy();
display.fillRect = sinon.spy();
@ -419,6 +419,27 @@ describe('Display/Canvas Helper', function () {
expect(img.addEventListener).to.have.been.calledOnce;
});
it('should wait if an image is incorrectly loaded', function () {
const img = { complete: true, width: 0, height: 0, addEventListener: sinon.spy() };
display._renderQ = [{ type: 'img', x: 3, y: 4, width: 4, height: 4, img: img },
{ type: 'fill', x: 1, y: 2, width: 3, height: 4, color: 5 }];
display.drawImage = sinon.spy();
display.fillRect = sinon.spy();
display._scan_renderQ();
expect(display.drawImage).to.not.have.been.called;
expect(display.fillRect).to.not.have.been.called;
expect(img.addEventListener).to.have.been.calledOnce;
display._renderQ[0].img.complete = true;
display._renderQ[0].img.width = 4;
display._renderQ[0].img.height = 4;
display._scan_renderQ();
expect(display.drawImage).to.have.been.calledOnce;
expect(display.fillRect).to.have.been.calledOnce;
expect(img.addEventListener).to.have.been.calledOnce;
});
it('should call callback when queue is flushed', function () {
display.onflush = sinon.spy();
display.fillRect(0, 0, 4, 4, [0, 0xff, 0]);