Implement perspective for bitmaps in pdf.

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 2010 matching lines @@
     SkAutoTUnref<SkPDFFont> newFont(SkPDFFont::GetFontResource(typeface, glyphID));
     int resourceIndex = fFontResources.find(newFont.get());
     if (resourceIndex < 0) {
         resourceIndex = fFontResources.count();
         fFontResources.push(newFont.get());
         newFont.get()->ref();
     }
     return resourceIndex;
 }
 
-void SkPDFDevice::internalDrawBitmap(const SkMatrix& matrix,
+static void setup_transparent_bitmap(SkBitmap* bitmap, int width, int height) {
+    bitmap->setConfig(SkBitmap::kARGB_8888_Config, width, height);
+    bitmap->allocPixels();
+    bitmap->eraseColor(SK_ColorTRANSPARENT);
+}
+
+void SkPDFDevice::internalDrawBitmap(const SkMatrix& origMatrix,
                                      const SkClipStack* clipStack,
-                                     const SkRegion& clipRegion,
-                                     const SkBitmap& bitmap,
-                                     const SkIRect* srcRect,
+                                     const SkRegion& origClipRegion,
+                                     const SkBitmap& origBitmap2,
+                                     const SkIRect* origSrcRect,
                                      const SkPaint& paint) {
-    // TODO(edisonn): Perspective matrix support implemented here
+    SkMatrix matrix = origMatrix;
+    SkRegion all;
+    const SkRegion* clipRegion = &origClipRegion;
+    SkBitmap origBitmap;
+    SkBitmap bitmap = origBitmap;
+    const SkIRect* srcRect = origSrcRect;
+
+    // Raster the bitmap using perspective in a new bitmap.
+    if (matrix.hasPerspective()) {
+        if (origSrcRect) {
+            if (!origBitmap2.extractSubset(&origBitmap, *origSrcRect)) {
+               return;
+            }
+        } else {
+            origBitmap = origBitmap2;
+        }
+        srcRect = NULL;
+
+        // Transform the bitmap in the new space.
+        SkPath path;
+        path.addRect(SkRect::MakeWH(SkIntToScalar(origBitmap.width()),
+                                    SkIntToScalar(origBitmap.height())));
+        path.transform(matrix);
+
+        // Retrieve the bounds of the new shape.
+        SkRect bounds = path.getBounds();

[vandebo (ex-Chrome), 2013/10/15 21:41:32]

Should this be further constrained by the current clip?

[edisonn, 2013/10/16 15:08:03]

This is an optimization. I will add a todo. in a non-perspective world all the
bitmap would have been saved. I would not make the perspective more efficient
than the non-perspective case.

+
+        // TODO(edisonn): add DPI settings. Currently 1 pixel/point, which does not look great,

[vandebo (ex-Chrome), 2013/10/15 21:41:32]

nit: 80 cols

[edisonn, 2013/10/16 15:08:03]

this file is already 100c

[vandebo (ex-Chrome), 2013/10/16 16:46:41]

Hardly, 31/2073 lines and most of those are over by one or two characters.

[edisonn, 2013/10/16 18:28:51]

Done.

+        // but it is not producing large PDFs.
+
+        // Create transparent bitmap.
+        setup_transparent_bitmap(&bitmap, bounds.width(), bounds.height());
+
+        SkAutoTUnref<SkBitmapDevice> device(SkNEW_ARGS(SkBitmapDevice, (bitmap)));
+        SkCanvas canvas(device);
+
+        // Find where (0,0) gets mapped in the new space.
+        SkPoint zeroZero = SkPoint::Make(SkIntToScalar(0), SkIntToScalar(0));

[vandebo (ex-Chrome), 2013/10/15 21:41:32]

zeroZero isn't used.

[edisonn, 2013/10/16 15:08:03]

Done.

+        matrix.mapPoints(&zeroZero, 1);
+
+        SkScalar deltaX = bounds.left();
+        SkScalar deltaY = bounds.top();
+
+        SkMatrix matrix2 = matrix;
+        matrix2.postTranslate(-deltaX, -deltaY);
+
+        // Translate the draw in the new canvas, so we perfectly fit the shape in the bitmap.
+        canvas.setMatrix(matrix2);
+
+        canvas.drawBitmap(origBitmap, SkIntToScalar(0), SkIntToScalar(0));
+
+        // Make sure the final bits ar in the bitmap.

[vandebo (ex-Chrome), 2013/10/15 21:41:32]

ar -> are

[edisonn, 2013/10/16 15:08:03]

Done.

+        canvas.flush();
+
+        // In the new space, we use the identity matrix translated.
+        matrix.setTranslate(deltaX, deltaY);
+        all.setRect(SkIRect::MakeXYWH(SkScalarToFixed(bounds.x()),
+                                      SkScalarToFixed(bounds.y()),
+                                      SkScalarToFixed(bounds.width()),
+                                      SkScalarToFixed(bounds.height())));
+        clipRegion = &all;
+        srcRect = NULL;
+    }
+
     SkMatrix scaled;
     // Adjust for origin flip.
     scaled.setScale(SK_Scalar1, -SK_Scalar1);
     scaled.postTranslate(0, SK_Scalar1);
     // Scale the image up from 1x1 to WxH.
     SkIRect subset = SkIRect::MakeWH(bitmap.width(), bitmap.height());
     scaled.postScale(SkIntToScalar(subset.width()),
                      SkIntToScalar(subset.height()));
     scaled.postConcat(matrix);
-    ScopedContentEntry content(this, clipStack, clipRegion, scaled, paint);
+
+    ScopedContentEntry content(this, clipStack, *clipRegion, scaled, paint);
     if (!content.entry()) {
         return;
     }
 
     if (srcRect && !subset.intersect(*srcRect)) {
         return;
     }
 
     SkPDFImage* image = SkPDFImage::CreateImage(bitmap, subset, fEncoder);
     if (!image) {
         return;
     }
 
     fXObjectResources.push(image);  // Transfer reference.
     SkPDFUtils::DrawFormXObject(fXObjectResources.count() - 1,
                                 &content.entry()->fContent);
 }
 
 bool SkPDFDevice::onReadPixels(const SkBitmap& bitmap, int x, int y,
                                SkCanvas::Config8888) {
     return false;
 }
 
 bool SkPDFDevice::allowImageFilter(SkImageFilter*) {
     return false;
 }