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

src/pdf/SkPDFDevice.cpp

Index: src/pdf/SkPDFDevice.cpp
diff --git a/src/pdf/SkPDFDevice.cpp b/src/pdf/SkPDFDevice.cpp
index 77aa7a353ce74ff5b0562238842751f94f2a22ce..6e88cdefd08d997a08f6ccef8a194b0b6d34119e 100644
--- a/src/pdf/SkPDFDevice.cpp
+++ b/src/pdf/SkPDFDevice.cpp
@@ -49,6 +49,8 @@ struct TypefaceFallbackData {
 };
 #endif
 
+#define DPI_FOR_RASTER_SCALE_ONE 72
+
 // Utility functions
 
 static void emit_pdf_color(SkColor color, SkWStream* result) {
@@ -2163,6 +2165,9 @@ void SkPDFDevice::internalDrawBitmap(const SkMatrix& origMatrix,
 
     // 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)) {
@@ -2185,9 +2190,15 @@ void SkPDFDevice::internalDrawBitmap(const SkMatrix& 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;
+
+        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();
 
-        // TODO(edisonn): add DPI settings. Currently 1 pixel/point, which does
-        // not look great, but it is not producing large PDFs.
+        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
@@ -2196,9 +2207,10 @@ void SkPDFDevice::internalDrawBitmap(const SkMatrix& origMatrix,
         // 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);
 
@@ -2210,6 +2222,7 @@ void SkPDFDevice::internalDrawBitmap(const SkMatrix& origMatrix,
 
         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.
@@ -2220,8 +2233,10 @@ void SkPDFDevice::internalDrawBitmap(const SkMatrix& origMatrix,
         // 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()),