add ability to specify the DPI at which to render the page

experimental/PdfViewer/SkPdfRenderer.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCanvas.h"
 #include "SkDevice.h"
 #include "SkForceLinking.h"
@@ skipping 1905 matching lines @@
 //      int formsCount();
 //      SkForm getForm(int formID); // SkForm(SkRect, .. other data)
 // TODO (edisonn): Add intend when loading pdf, for example: for viewing, parsing all content, ...
 // if we load the first page, and we zoom to fit to screen horizontally, then load only those
 // resources needed, so the preview is fast.
 // TODO (edisonn): hide parser/tokenizer behind and interface and a query language, and resolve
 // references automatically.
 
 PdfContext* gPdfContext = NULL;
 
-bool SkPdfRenderer::renderPage(int page, SkCanvas* canvas) const {
+bool SkPdfRenderer::renderPage(int page, SkCanvas* canvas, const SkRect& dst) const {
     if (!fPdfDoc) {
         return false;
     }
 
     if (page < 0 || page >= pages()) {
         return false;
     }
 
     SkPdfNativeTokenizer* tokenizer = fPdfDoc->tokenizerOfPage(page);
 
     PdfContext pdfContext(fPdfDoc);
     pdfContext.fOriginalMatrix = SkMatrix::I();
     pdfContext.fGraphicsState.fResources = fPdfDoc->pageResources(page);
 
     gPdfContext = &pdfContext;
 
     // TODO(edisonn): get matrix stuff right.
-    // TODO(edisonn): add DPI/scale/zoom.
     SkScalar z = SkIntToScalar(0);
-    SkRect rect = fPdfDoc->MediaBox(page);
-    SkScalar w = rect.width();
-    SkScalar h = rect.height();
+    SkScalar w = dst.width();
+    SkScalar h = dst.height();
 
-    SkPoint pdfSpace[4] = {SkPoint::Make(z, z), SkPoint::Make(w, z), SkPoint::Make(w, h), SkPoint::Make(z, h)};
+    SkScalar wp = fPdfDoc->MediaBox(page).width();
+    SkScalar hp = fPdfDoc->MediaBox(page).height();
+
+    SkPoint pdfSpace[4] = {SkPoint::Make(z, z), SkPoint::Make(wp, z), SkPoint::Make(wp, hp), SkPoint::Make(z, hp)};
 //                SkPoint skiaSpace[4] = {SkPoint::Make(z, h), SkPoint::Make(w, h), SkPoint::Make(w, z), SkPoint::Make(z, z)};
 
     // TODO(edisonn): add flag for this app to create sourunding buffer zone
     // TODO(edisonn): add flagg for no clipping.
     // Use larger image to make sure we do not draw anything outside of page
     // could be used in tests.
 
 #ifdef PDF_DEBUG_3X
     SkPoint skiaSpace[4] = {SkPoint::Make(w+z, h+h), SkPoint::Make(w+w, h+h), SkPoint::Make(w+w, h+z), SkPoint::Make(w+z, h+z)};
 #else
     SkPoint skiaSpace[4] = {SkPoint::Make(z, h), SkPoint::Make(w, h), SkPoint::Make(w, z), SkPoint::Make(z, z)};
 #endif
     //SkPoint pdfSpace[2] = {SkPoint::Make(z, z), SkPoint::Make(w, h)};
     //SkPoint skiaSpace[2] = {SkPoint::Make(w, z), SkPoint::Make(z, h)};
 
     //SkPoint pdfSpace[2] = {SkPoint::Make(z, z), SkPoint::Make(z, h)};
     //SkPoint skiaSpace[2] = {SkPoint::Make(z, h), SkPoint::Make(z, z)};
 
     //SkPoint pdfSpace[3] = {SkPoint::Make(z, z), SkPoint::Make(z, h), SkPoint::Make(w, h)};
     //SkPoint skiaSpace[3] = {SkPoint::Make(z, h), SkPoint::Make(z, z), SkPoint::Make(w, 0)};
 
     SkAssertResult(pdfContext.fOriginalMatrix.setPolyToPoly(pdfSpace, skiaSpace, 4));
     SkTraceMatrix(pdfContext.fOriginalMatrix, "Original matrix");
 
 
     pdfContext.fGraphicsState.fMatrix = pdfContext.fOriginalMatrix;
     pdfContext.fGraphicsState.fMatrixTm = pdfContext.fGraphicsState.fMatrix;
     pdfContext.fGraphicsState.fMatrixTlm = pdfContext.fGraphicsState.fMatrix;
 
+#ifndef PDF_DEBUG_NO_PAGE_CLIPING
+    canvas->clipRect(dst, SkRegion::kIntersect_Op, true);
+#endif
+
     canvas->setMatrix(pdfContext.fOriginalMatrix);
 
-#ifndef PDF_DEBUG_NO_PAGE_CLIPING
-    canvas->clipRect(SkRect::MakeXYWH(z, z, w, h), SkRegion::kIntersect_Op, true);
-#endif
-
 // erase with red before?
 //        SkPaint paint;
 //        paint.setColor(SK_ColorRED);
 //        canvas->drawRect(rect, paint);
 
     PdfMainLooper looper(NULL, tokenizer, &pdfContext, canvas);
     looper.loop();
 
     delete tokenizer;
 
@@ skipping 21 matching lines @@
 
 SkRect SkPdfRenderer::MediaBox(int page) const {
     SkASSERT(fPdfDoc);
     return fPdfDoc->MediaBox(page);
 }
 
 size_t SkPdfRenderer::bytesUsed() const {
     return fPdfDoc ? fPdfDoc->bytesUsed() : 0;
 }