Implement DPI for perspective bitmaps in PDF - we save the bitmap at the resolution requested.

src/pdf/SkPDFDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPDFDevice.h"
 
 #include "SkAnnotation.h"
@@ skipping 31 matching lines @@
     int upperBounds;
 
     bool operator==(const TypefaceFallbackData& b) const {
         return typeface == b.typeface &&
                lowerBounds == b.lowerBounds &&
                upperBounds == b.upperBounds;
     }
 };
 #endif
 
+#define DPI_FOR_RASTER_SCALE_ONE 72
+
 // Utility functions
 
 static void emit_pdf_color(SkColor color, SkWStream* result) {
     SkASSERT(SkColorGetA(color) == 0xFF);  // We handle alpha elsewhere.
     SkScalar colorMax = SkIntToScalar(0xFF);
     SkPDFScalar::Append(
             SkScalarDiv(SkIntToScalar(SkColorGetR(color)), colorMax), result);
     result->writeText(" ");
     SkPDFScalar::Append(
             SkScalarDiv(SkIntToScalar(SkColorGetG(color)), colorMax), result);
@@ skipping 2094 matching lines @@
                                      const SkPaint& paint) {
     SkMatrix matrix = origMatrix;
     SkRegion perspectiveBounds;
     const SkRegion* clipRegion = &origClipRegion;
     SkBitmap perspectiveBitmap;
     const SkBitmap* bitmap = &origBitmap;
     SkBitmap tmpSubsetBitmap;
 
     // Rasterize the bitmap using perspective in a new bitmap.
     if (origMatrix.hasPerspective()) {
+        if (fRasterDpi == 0) {
+            return;
+        }
         SkBitmap* subsetBitmap;
         if (srcRect) {
             if (!origBitmap.extractSubset(&tmpSubsetBitmap, *srcRect)) {
                return;
             }
             subsetBitmap = &tmpSubsetBitmap;
         } else {
             subsetBitmap = &tmpSubsetBitmap;
             *subsetBitmap = origBitmap;
         }
         srcRect = NULL;
 
         // Transform the bitmap in the new space.
         SkPath perspectiveOutline;
         perspectiveOutline.addRect(
                 SkRect::MakeWH(SkIntToScalar(subsetBitmap->width()),
                                SkIntToScalar(subsetBitmap->height())));
         perspectiveOutline.transform(origMatrix);
 
         // TODO(edisonn): perf - use current clip too.
         // Retrieve the bounds of the new shape.
         SkRect bounds = perspectiveOutline.getBounds();
+        SkScalar scaleX = SkIntToScalar(fRasterDpi) /
+                              SkIntToScalar(DPI_FOR_RASTER_SCALE_ONE);
+        SkScalar scaleY = scaleX;
 
-        // TODO(edisonn): add DPI settings. Currently 1 pixel/point, which does
-        // not look great, but it is not producing large PDFs.
+        scaleX *= fInitialTransform.getScaleX();

[vandebo (ex-Chrome), 2013/11/04 19:55:10]

The initial transform is already applied to the canvas, so we do need to account
for the initial transform when calculating the scale factor for the DPI... see
comment on line 2237

[edisonn, 2013/11/05 20:33:32]

Done.

+        scaleY *= fInitialTransform.getScaleY();
+
+        scaleX = SkScalarAbs(scaleX);
+        scaleY = SkScalarAbs(scaleY);
 
         // TODO(edisonn): A better approach would be to use a bitmap shader
         // (in clamp mode) and draw a rect over the entire bounding box. Then
         // intersect perspectiveOutline to the clip. That will avoid introducing
         // alpha to the image while still giving good behavior at the edge of
         // the image.  Avoiding alpha will reduce the pdf size and generation
         // CPU time some.
 
-        perspectiveBitmap.setConfig(SkBitmap::kARGB_8888_Config,
-                                    SkScalarCeilToInt(bounds.width()),
-                                    SkScalarCeilToInt(bounds.height()));
+        perspectiveBitmap.setConfig(
+                SkBitmap::kARGB_8888_Config,
+                SkScalarCeilToInt(scaleX * bounds.width()),

[vandebo (ex-Chrome), 2013/11/04 19:55:10]

Apply Abs here instead of on 2200 so you don't have to do it again on 2237.

... SkScalarAbs(scaleX) ....

[edisonn, 2013/11/05 20:33:32]

Done.

+                SkScalarCeilToInt(scaleY * bounds.height()));
         perspectiveBitmap.allocPixels();
         perspectiveBitmap.eraseColor(SK_ColorTRANSPARENT);
 
         SkBitmapDevice device(perspectiveBitmap);
         SkCanvas canvas(&device);
 
         SkScalar deltaX = bounds.left();
         SkScalar deltaY = bounds.top();
 
         SkMatrix offsetMatrix = origMatrix;
         offsetMatrix.postTranslate(-deltaX, -deltaY);
+        offsetMatrix.postScale(scaleX, scaleY);

[vandebo (ex-Chrome), 2013/11/04 19:55:10]

I'm not sure if you need to unapply the initial transform scaling before or
after this line.

[edisonn, 2013/11/05 20:33:32]

Done.

 
         // Translate the draw in the new canvas, so we perfectly fit the
         // shape in the bitmap.
         canvas.setMatrix(offsetMatrix);
 
         canvas.drawBitmap(*subsetBitmap, SkIntToScalar(0), SkIntToScalar(0));
 
         // Make sure the final bits are in the bitmap.
         canvas.flush();
 
-        // In the new space, we use the identity matrix translated.
-        matrix.setTranslate(deltaX, deltaY);
+        // In the new space, we use the identity matrix translated
+        // and scaled to reflect DPI.

[vandebo (ex-Chrome), 2013/11/04 19:55:10]

But we need to unapply it here so that it doesn't get applied twice (since it's
already on the canvas):

scaleX /= fInitialTransform.getScaleX();
scaleY /= fInitialTransform.getScaleY();

[edisonn, 2013/11/05 20:33:32]

Done.

+        matrix.setScale(1 / scaleX, 1 / scaleY);
+        matrix.postTranslate(deltaX, deltaY);
         perspectiveBounds.setRect(
                 SkIRect::MakeXYWH(SkScalarFloorToInt(bounds.x()),
                                   SkScalarFloorToInt(bounds.y()),
                                   SkScalarCeilToInt(bounds.width()),
                                   SkScalarCeilToInt(bounds.height())));
         clipRegion = &perspectiveBounds;
         srcRect = NULL;
         bitmap = &perspectiveBitmap;
     }
 
@@ skipping 32 matching lines @@
 }
 
 bool SkPDFDevice::onReadPixels(const SkBitmap& bitmap, int x, int y,
                                SkCanvas::Config8888) {
     return false;
 }
 
 bool SkPDFDevice::allowImageFilter(SkImageFilter*) {
     return false;
 }