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Add basic support for transparency groups.

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This commit is contained in:
Brendan Dahl 2013-03-12 17:20:38 -07:00
parent 3f195f3308
commit 725cd5407f
6 changed files with 2318 additions and 26 deletions
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105
src/canvas.js
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@ -16,7 +16,7 @@
*/
/* globals ColorSpace, DeviceCmykCS, DeviceGrayCS, DeviceRgbCS, error,
FONT_IDENTITY_MATRIX, IDENTITY_MATRIX, ImageData, isArray, isNum,
isString, Pattern, TilingPattern, TODO, Util, warn */
isString, Pattern, TilingPattern, TODO, Util, warn, assert */
'use strict';
@ -225,6 +225,7 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
this.objs = objs;
this.textLayer = textLayer;
this.imageLayer = imageLayer;
this.groupStack = [];
if (canvasCtx) {
addContextCurrentTransform(canvasCtx);
}
@ -357,6 +358,25 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
return tmpCanvas;
}
function copyCtxState(sourceCtx, destCtx) {
var properties = ['strokeStyle', 'fillStyle', 'fillRule', 'globalAlpha',
'lineWidth', 'lineCap', 'lineJoin', 'miterLimit',
'globalCompositeOperation', 'font'];
for (var i = 0, ii = properties.length; i < ii; i++) {
var property = properties[i];
if (property in sourceCtx) {
destCtx[property] = sourceCtx[property];
}
}
if ('setLineDash' in sourceCtx) {
destCtx.setLineDash(sourceCtx.getLineDash());
destCtx.lineDashOffset = sourceCtx.lineDashOffset;
} else if ('mozDash' in sourceCtx) {
destCtx.mozDash = sourceCtx.mozDash;
destCtx.mozDashOffset = sourceCtx.mozDashOffset;
}
}
var LINE_CAP_STYLES = ['butt', 'round', 'square'];
var LINE_JOIN_STYLES = ['miter', 'round', 'bevel'];
var NORMAL_CLIP = {};
@ -1347,6 +1367,89 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
} while (this.current.paintFormXObjectDepth >= depth);
},
beginGroup: function CanvasGraphics_beginGroup(group) {
this.save();
var currentCtx = this.ctx;
// TODO non-isolated groups - according to Rik at adobe non-isolated
// group results aren't usually that different and they even have tools
// that ignore this setting. Notes from Rik on implmenting:
// - When you encounter an transparency group, create a new canvas with
// the dimensions of the bbox
// - copy the content from the previous canvas to the new canvas
// - draw as usual
// - remove the backdrop alpha:
// alphaNew = 1 - (1 - alpha)/(1 - alphaBackdrop) with 'alpha' the alpha
// value of your transparency group and 'alphaBackdrop' the alpha of the
// backdrop
// - remove background color:
// colorNew = color - alphaNew *colorBackdrop /(1 - alphaNew)
if (!group.isolated) {
TODO('Support non-isolated groups.');
}
// TODO knockout - supposedly possible with the clever use of compositing
// modes.
if (group.knockout) {
TODO('Support knockout groups.');
}
var currentTransform = currentCtx.mozCurrentTransform;
if (group.matrix) {
currentCtx.transform.apply(currentCtx, group.matrix);
}
assert(group.bbox, 'Bounding box is required.');
// Based on the current transform figure out how big the bounding box
// will actually be.
var bounds = Util.getAxialAlignedBoundingBox(
group.bbox,
currentCtx.mozCurrentTransform);
// Use ceil in case we're between sizes so we don't create canvas that is
// too small.
var drawnWidth = Math.ceil(bounds[2] - bounds[0]);
var drawnHeight = Math.ceil(bounds[3] - bounds[1]);
var scratchCanvas = createScratchCanvas(drawnWidth, drawnHeight);
var groupCtx = scratchCanvas.getContext('2d');
addContextCurrentTransform(groupCtx);
// Since we created a new canvas that is just the size of the bounding box
// we have to translate the group ctx.
var offsetX = bounds[0];
var offsetY = bounds[1];
groupCtx.translate(-offsetX, -offsetY);
groupCtx.transform.apply(groupCtx, currentTransform);
// Setup the current ctx so when the group is popped we draw it the right
// location.
currentCtx.setTransform(1, 0, 0, 1, 0, 0);
currentCtx.translate(offsetX, offsetY);
// The transparency group inherits all off the current graphics state
// except the blend mode, soft mask, and alpha constants.
copyCtxState(currentCtx, groupCtx);
this.ctx = groupCtx;
this.setGState([
['SMask', 'None'],
['BM', 'Normal'],
['ca', 1],
['CA', 1]
]);
this.groupStack.push(currentCtx);
},
endGroup: function CanvasGraphics_endGroup(group) {
var groupCtx = this.ctx;
this.ctx = this.groupStack.pop();
// Turn off image smoothing to avoid sub pixel interpolation which can
// look kind of blurry for some pdfs.
if ('imageSmoothingEnabled' in this.ctx) {
this.ctx.imageSmoothingEnabled = false;
} else {
this.ctx.mozImageSmoothingEnabled = false;
}
this.ctx.drawImage(groupCtx.canvas, 0, 0);
this.restore();
},
paintJpegXObject: function CanvasGraphics_paintJpegXObject(objId, w, h) {
var domImage = this.objs.get(objId);
if (!domImage) {

77
src/evaluator.js
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@ -244,6 +244,60 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
return loadedName;
}
function buildFormXObject(xobj, smask) {
var matrix = xobj.dict.get('Matrix');
var bbox = xobj.dict.get('BBox');
var group = xobj.dict.get('Group');
if (group) {
var groupOptions = {
matrix: matrix,
bbox: bbox,
smask: !!smask,
isolated: false,
knockout: false
};
var groupSubtype = group.get('S');
if (isName(groupSubtype) && groupSubtype.name === 'Transparency') {
groupOptions.isolated = group.get('I') || false;
groupOptions.knockout = group.get('K') || false;
// There is also a group colorspace, but since we put everything in
// RGB I'm not sure we need it.
}
fnArray.push('beginGroup');
argsArray.push([groupOptions]);
}
fnArray.push('paintFormXObjectBegin');
argsArray.push([matrix, bbox]);
// This adds the operatorList of the xObj to the current queue.
var depIdx = dependencyArray.length;
// Pass in the current `queue` object. That means the `fnArray`
// and the `argsArray` in this scope is reused and new commands
// are added to them.
self.getOperatorList(xobj,
xobj.dict.get('Resources') || resources,
dependencyArray, queue);
self.getOperatorList(xobj,
xobj.dict.get('Resources') || resources,
dependencyArray, queue);
// Add the dependencies that are required to execute the
// operatorList.
insertDependency(dependencyArray.slice(depIdx));
fnArray.push('paintFormXObjectEnd');
argsArray.push([]);
if (group) {
fnArray.push('endGroup');
argsArray.push([groupOptions]);
}
}
function buildPaintImageXObject(image, inline) {
var dict = image.dict;
var w = dict.get('Width', 'W');
@ -417,28 +471,9 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
);
if ('Form' == type.name) {
var matrix = xobj.dict.get('Matrix');
var bbox = xobj.dict.get('BBox');
fnArray.push('paintFormXObjectBegin');
argsArray.push([matrix, bbox]);
// This adds the operatorList of the xObj to the current queue.
var depIdx = dependencyArray.length;
// Pass in the current `queue` object. That means the `fnArray`
// and the `argsArray` in this scope is reused and new commands
// are added to them.
this.getOperatorList(xobj,
xobj.dict.get('Resources') || resources,
dependencyArray, queue);
// Add the dependencies that are required to execute the
// operatorList.
insertDependency(dependencyArray.slice(depIdx));
fn = 'paintFormXObjectEnd';
buildFormXObject(xobj);
args = [];
continue;
} else if ('Image' == type.name) {
buildPaintImageXObject(xobj, false);
} else {

17
src/util.js
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@ -237,6 +237,23 @@ var Util = PDFJS.Util = (function UtilClosure() {
return [xt, yt];
};
// Applies the transform to the rectangle and finds the minimum axially
// aligned bounding box.
Util.getAxialAlignedBoundingBox =
function Util_getAxialAlignedBoundingBox(r, m) {
var p1 = Util.applyTransform(r, m);
var p2 = Util.applyTransform(r.slice(2, 4), m);
var p3 = Util.applyTransform([r[0], r[3]], m);
var p4 = Util.applyTransform([r[2], r[1]], m);
return [
Math.min(p1[0], p2[0], p3[0], p4[0]),
Math.min(p1[1], p2[1], p3[1], p4[1]),
Math.max(p1[0], p2[0], p3[0], p4[0]),
Math.max(p1[1], p2[1], p3[1], p4[1])
];
};
Util.inverseTransform = function Util_inverseTransform(m) {
var d = m[0] * m[3] - m[1] * m[2];
return [m[3] / d, -m[1] / d, -m[2] / d, m[0] / d,

2134
test/pdfs/transparency_group.pdf Normal file
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File diff suppressed because one or more lines are too long

7
test/test_manifest.json
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@ -845,6 +845,13 @@
"type": "eq",
"about": "Every blend mode that PDF supports."
},
{ "id": "transparency_group",
"file": "pdfs/transparency_group.pdf",
"md5": "10391f76434128e5da70cff5fc485ff0",
"rounds": 1,
"type": "eq",
"about": "Rotated transparency group with blend mode."
},
{ "id": "issue2462",
"file": "pdfs/issue2462.pdf",
"md5": "d4e3dddfdd35464c71cf0310bff29b42",

4
web/viewer.js
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@ -2145,10 +2145,6 @@ var PageView = function pageView(container, pdfPage, id, scale,
// TODO(mack): use data attributes to store these
ctx._scaleX = outputScale.sx;
ctx._scaleY = outputScale.sy;
ctx.save();
ctx.fillStyle = 'rgb(255, 255, 255)';
ctx.fillRect(0, 0, canvas.width, canvas.height);
ctx.restore();
if (outputScale.scaled) {
ctx.scale(outputScale.sx, outputScale.sy);
}