Fix FPDF_RenderPageBitmapWithMatrix

This CL fixes FPDF_RenderPageBitmapWithMatrix and improves tests.

Bug: pdfium:837
Change-Id: I98f90b667cc9a50fb0e915b8a758603488b44d40
Reviewed-on: https://pdfium-review.googlesource.com/9010
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>

4 files changed, 127 insertions, 17 deletions

diff --git a/fpdfsdk/fpdfview.cpp b/fpdfsdk/fpdfview.cpp
index 956e6db671..c51ee90fe0 100644
--- a/fpdfsdk/fpdfview.cpp
+++ b/fpdfsdk/fpdfview.cpp
@@ -967,12 +967,6 @@ DLLEXPORT void STDCALL FPDF_RenderPageBitmapWithMatrix(FPDF_BITMAP bitmap,
   CFX_RetainPtr<CFX_DIBitmap> pBitmap(CFXBitmapFromFPDFBitmap(bitmap));
   pDevice->Attach(pBitmap, !!(flags & FPDF_REVERSE_BYTE_ORDER), nullptr, false);
 
-  CFX_Matrix transform_matrix = pPage->GetPageMatrix();
-  if (matrix) {
-    transform_matrix.Concat(CFX_Matrix(matrix->a, matrix->b, matrix->c,
-                                       matrix->d, matrix->e, matrix->f));
-  }
-
   CFX_FloatRect clipping_rect;
   if (clipping) {
     clipping_rect.left = clipping->left;
@@ -980,8 +974,16 @@ DLLEXPORT void STDCALL FPDF_RenderPageBitmapWithMatrix(FPDF_BITMAP bitmap,
     clipping_rect.right = clipping->right;
     clipping_rect.top = clipping->top;
   }
-  RenderPageImpl(pContext, pPage, transform_matrix, clipping_rect.ToFxRect(),
-                 flags, true, nullptr);
+  FX_RECT clip_rect = clipping_rect.ToFxRect();
+
+  CFX_Matrix transform_matrix = pPage->GetDisplayMatrix(
+      clip_rect.left, clip_rect.top, clip_rect.Width(), clip_rect.Height(), 0);
+  if (matrix) {
+    transform_matrix.Concat(CFX_Matrix(matrix->a, matrix->b, matrix->c,
+                                       matrix->d, matrix->e, matrix->f));
+  }
+  RenderPageImpl(pContext, pPage, transform_matrix, clip_rect, flags, true,
+                 nullptr);
 
   pPage->SetRenderContext(nullptr);
 }
diff --git a/fpdfsdk/fpdfview_embeddertest.cpp b/fpdfsdk/fpdfview_embeddertest.cpp
index f36edbc4d6..a986a1cd96 100644
--- a/fpdfsdk/fpdfview_embeddertest.cpp
+++ b/fpdfsdk/fpdfview_embeddertest.cpp
@@ -330,19 +330,21 @@ TEST_F(FPDFViewEmbeddertest, Hang_360) {
 }
 
 TEST_F(FPDFViewEmbeddertest, FPDF_RenderPageBitmapWithMatrix) {
-  const char kAllBlackMd5sum[] = "5708fc5c4a8bd0abde99c8e8f0390615";
-  const char kTopLeftQuarterBlackMd5sum[] = "24e4d1ec06fa0258af758cfc8b2ad50a";
+  const char kOriginalMD5[] = "210157942bcce97b057a1107a1fd62f8";
+  const char kTopLeftQuarterMD5[] = "c54d58dda13e3cd04eb63e1d0db0feda";
+  const char kTrimmedMD5[] = "88225d7951a21d0eef191cfed06c36ce";
+  const char kRotatedMD5[] = "7d38bc58aa50ad271bc432e77256d3de";
 
-  EXPECT_TRUE(OpenDocument("black.pdf"));
+  EXPECT_TRUE(OpenDocument("rectangles.pdf"));
   FPDF_PAGE page = LoadPage(0);
   EXPECT_NE(nullptr, page);
   const int width = static_cast<int>(FPDF_GetPageWidth(page));
   const int height = static_cast<int>(FPDF_GetPageHeight(page));
-  EXPECT_EQ(612, width);
-  EXPECT_EQ(792, height);
+  EXPECT_EQ(200, width);
+  EXPECT_EQ(200, height);
 
   FPDF_BITMAP bitmap = RenderPage(page);
-  CompareBitmap(bitmap, width, height, kAllBlackMd5sum);
+  CompareBitmap(bitmap, width, height, kOriginalMD5);
   FPDFBitmap_Destroy(bitmap);
 
   // Try rendering with an identity matrix. The output should be the same as
@@ -364,17 +366,39 @@ TEST_F(FPDFViewEmbeddertest, FPDF_RenderPageBitmapWithMatrix) {
   bitmap = FPDFBitmap_Create(width, height, 0);
   FPDFBitmap_FillRect(bitmap, 0, 0, width, height, 0xFFFFFFFF);
   FPDF_RenderPageBitmapWithMatrix(bitmap, page, &matrix, &rect, 0);
-  CompareBitmap(bitmap, width, height, kAllBlackMd5sum);
+  CompareBitmap(bitmap, width, height, kOriginalMD5);
   FPDFBitmap_Destroy(bitmap);
 
-  // Now render again with the image scaled.
+  // Now render again with the image scaled smaller.
   matrix.a = 0.5;
   matrix.d = 0.5;
 
   bitmap = FPDFBitmap_Create(width, height, 0);
   FPDFBitmap_FillRect(bitmap, 0, 0, width, height, 0xFFFFFFFF);
   FPDF_RenderPageBitmapWithMatrix(bitmap, page, &matrix, &rect, 0);
-  CompareBitmap(bitmap, width, height, kTopLeftQuarterBlackMd5sum);
+  CompareBitmap(bitmap, width, height, kTopLeftQuarterMD5);
+  FPDFBitmap_Destroy(bitmap);
+
+  // Now render again with the image scaled larger horizontally (will be
+  // trimmed).
+  matrix.a = 2;
+  matrix.d = 1;
+  bitmap = FPDFBitmap_Create(width, height, 0);
+  FPDFBitmap_FillRect(bitmap, 0, 0, width, height, 0xFFFFFFFF);
+  FPDF_RenderPageBitmapWithMatrix(bitmap, page, &matrix, &rect, 0);
+  CompareBitmap(bitmap, width, height, kTrimmedMD5);
+  FPDFBitmap_Destroy(bitmap);
+
+  // Now try a 90 degree rotation
+  matrix.a = 0;
+  matrix.b = 1;
+  matrix.c = -1;
+  matrix.d = 0;
+  matrix.e = width;
+  bitmap = FPDFBitmap_Create(width, height, 0);
+  FPDFBitmap_FillRect(bitmap, 0, 0, width, height, 0xFFFFFFFF);
+  FPDF_RenderPageBitmapWithMatrix(bitmap, page, &matrix, &rect, 0);
+  CompareBitmap(bitmap, width, height, kRotatedMD5);
   FPDFBitmap_Destroy(bitmap);
 
   UnloadPage(page);
diff --git a/testing/resources/rectangles.in b/testing/resources/rectangles.in
new file mode 100644
index 0000000000..ed71cf830a
--- /dev/null
+++ b/testing/resources/rectangles.in
@@ -0,0 +1,38 @@
+{{header}}
+{{object 1 0}} <<
+  /Type /Catalog
+  /Pages 2 0 R
+>>
+endobj
+{{object 2 0}} <<
+  /Type /Pages
+  /MediaBox [ 0 0 200 200 ]
+  /Count 1
+  /Kids [ 3 0 R ]
+>>
+endobj
+{{object 3 0}} <<
+  /Type /Page
+  /Parent 2 0 R
+  /Contents 4 0 R
+>>
+endobj
+{{object 4 0}} <<
+>>
+stream
+q
+0 0 0 rg
+10 80 50 30 re B*
+0 0 1 rg
+70 135 50 30 re B*
+0 1 0 rg
+130 80 50 30 re B*
+1 0 0 rg
+70 25 50 30 re B*
+Q
+endstream
+endobj
+{{xref}}
+{{trailer}}
+{{startxref}}
+%%EOF
diff --git a/testing/resources/rectangles.pdf b/testing/resources/rectangles.pdf
new file mode 100644
index 0000000000..718bee56d9
--- /dev/null
+++ b/testing/resources/rectangles.pdf
@@ -0,0 +1,46 @@
+%PDF-1.7
+% ò¤ô
+1 0 obj <<
+  /Type /Catalog
+  /Pages 2 0 R
+>>
+endobj
+2 0 obj <<
+  /Type /Pages
+  /MediaBox [ 0 0 200 200 ]
+  /Count 1
+  /Kids [ 3 0 R ]
+>>
+endobj
+3 0 obj <<
+  /Type /Page
+  /Parent 2 0 R
+  /Contents 4 0 R
+>>
+endobj
+4 0 obj <<
+>>
+stream
+q
+0 0 0 rg
+10 80 50 30 re B*
+0 0 1 rg
+70 135 50 30 re B*
+0 1 0 rg
+130 80 50 30 re B*
+1 0 0 rg
+70 25 50 30 re B*
+Q
+endstream
+endobj
+xref
+0 5
+0000000000 65535 f 
+0000000015 00000 n 
+0000000068 00000 n 
+0000000161 00000 n 
+0000000230 00000 n 
+trailer<< /Root 1 0 R /Size 5 >>
+startxref
+382
+%%EOF