Add GetCanvasSize() method to mux

Change-Id: If910f5024f4c301a92e6c2e8ee9c315a103c5df7

NEWS

@@ -1,5 +1,6 @@
 - Next version:
   * Add incremental decoding support for images containing ALPH and ICCP chunks.
+  * New function: WebPMuxGetCanvasSize
 
 - 3/20/13: version 0.3.0
   This is a binary compatible release.

examples/webpmux.c

@@ -180,9 +180,14 @@ static const char* ErrorString(WebPMuxError err) {
   } while (0)
 
 static WebPMuxError DisplayInfo(const WebPMux* mux) {
+  int width, height;
   uint32_t flag;
 
-  WebPMuxError err = WebPMuxGetFeatures(mux, &flag);
+  WebPMuxError err = WebPMuxGetCanvasSize(mux, &width, &height);
+  RETURN_IF_ERROR("Failed to retrieve canvas width/height.\n");
+  printf("Canvas size: %d x %d\n", width, height);
+
+  err = WebPMuxGetFeatures(mux, &flag);
 #ifndef WEBP_EXPERIMENTAL_FEATURES
   if (flag & FRAGMENTS_FLAG) err = WEBP_MUX_INVALID_ARGUMENT;
 #endif

src/mux/muxi.h

@@ -236,6 +236,12 @@ WebPChunk** MuxGetChunkListFromId(const WebPMux* mux, WebPChunkId id);
 // Validates that the given mux has a single image.
 WebPMuxError MuxValidateForImage(const WebPMux* const mux);
 
+// Get the canvas width and height after validating that VP8X/VP8/VP8L chunk and
+// canvas size are valid. This method can be used for validation-only purposes
+// by passing 'width' and 'height' to be NULL.
+WebPMuxError MuxGetCanvasSize(const WebPMux* const mux, int* width,
+                              int* height);
+
 // Validates the given mux object.
 WebPMuxError MuxValidate(const WebPMux* const mux);
 

src/mux/muxinternal.c

@@ -503,6 +503,10 @@ WebPMuxError MuxValidate(const WebPMux* const mux) {
   // Verify mux has at least one image.
   if (mux->images_ == NULL) return WEBP_MUX_INVALID_ARGUMENT;
 
+  // Validate that VP8X/VP8/VP8L chunk and canvas size are valid.
+  err = MuxGetCanvasSize(mux, NULL, NULL);
+  if (err != WEBP_MUX_OK) return err;
+
   err = WebPMuxGetFeatures(mux, &flags);
   if (err != WEBP_MUX_OK) return err;
 

src/mux/muxread.c

@@ -260,6 +260,38 @@ WebPMux* WebPMuxCreateInternal(const WebPData* bitstream, int copy_data,
 //------------------------------------------------------------------------------
 // Get API(s).
 
+WebPMuxError MuxGetCanvasSize(const WebPMux* const mux, int* width,
+                              int* height) {
+  int w, h;
+  WebPData data;
+  assert(mux != NULL);
+
+  // Check if VP8X chunk is present.
+  if (MuxGet(mux, IDX_VP8X, 1, &data) == WEBP_MUX_OK) {
+    if (data.size < VP8X_CHUNK_SIZE) return WEBP_MUX_BAD_DATA;
+    w = GetLE24(data.bytes + 4) + 1;
+    h = GetLE24(data.bytes + 7) + 1;
+  } else {  // Single image case.
+    WebPMuxError err = MuxValidateForImage(mux);
+    if (err != WEBP_MUX_OK) return err;
+    err = MuxGetImageWidthHeight(mux->images_->img_, &w, &h);
+    if (err != WEBP_MUX_OK) return err;
+  }
+  if (w * (uint64_t)h >= MAX_IMAGE_AREA) return WEBP_MUX_BAD_DATA;
+
+  if (width) *width = w;
+  if (height) *height = h;
+  return WEBP_MUX_OK;
+}
+
+WebPMuxError WebPMuxGetCanvasSize(const WebPMux* mux, int* width, int* height) {
+  if (mux == NULL || width == NULL || height == NULL) {
+    return WEBP_MUX_INVALID_ARGUMENT;
+  }
+  return MuxGetCanvasSize(mux, width, height);
+}
+
+
 WebPMuxError WebPMuxGetFeatures(const WebPMux* mux, uint32_t* flags) {
   WebPData data;
 

src/webp/mux.h

@@ -51,7 +51,7 @@
 extern "C" {
 #endif
 
-#define WEBP_MUX_ABI_VERSION 0x0100        // MAJOR(8b) + MINOR(8b)
+#define WEBP_MUX_ABI_VERSION 0x0101        // MAJOR(8b) + MINOR(8b)
 
 // Note: forward declaring enumerations is not allowed in (strict) C and C++,
 // the types are left here for reference.
@@ -303,7 +303,25 @@ WEBP_EXTERN(WebPMuxError) WebPMuxGetAnimationParams(
 //------------------------------------------------------------------------------
 // Misc Utilities.
 
+// Gets the canvas size from the mux object.
+// Note: This method assumes that VP8X chunk, if present, is up-to-date. That
+// is, the mux object hasn't been modified since the last call to
+// WebPMuxAssemble() or WebMuxCreate().
+// Parameters:
+//   mux - (in) object from which the canvas size is to be fetched
+//   width - (out) canvas width
+//   height - (out) canvas height
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux, width or height is NULL
+//   WEBP_MUX_BAD_DATA - if VP8X/VP8/VP8L chunk or canvas size is invalid.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxGetCanvasSize(const WebPMux* mux,
+                                               int* width, int* height);
+
 // Gets the feature flags from the mux object.
+// Note: This method assumes that VP8X chunk, if present, is up-to-date. That
+// is, the mux object hasn't been modified since the last call to
+// WebPMuxAssemble() or WebMuxCreate().
 // Parameters:
 //   mux - (in) object from which the features are to be fetched
 //   flags - (out) the flags specifying which features are present in the
@@ -311,8 +329,7 @@ WEBP_EXTERN(WebPMuxError) WebPMuxGetAnimationParams(
 //           Enum 'WebPFeatureFlags' can be used to test individual flag values.
 // Returns:
 //   WEBP_MUX_INVALID_ARGUMENT - if mux or flags is NULL
-//   WEBP_MUX_NOT_FOUND - if VP8X chunk is not present in mux object.
-//   WEBP_MUX_BAD_DATA - if VP8X chunk in mux is invalid.
+//   WEBP_MUX_BAD_DATA - if VP8X/VP8L chunk in mux is invalid.
 //   WEBP_MUX_OK - on success.
 WEBP_EXTERN(WebPMuxError) WebPMuxGetFeatures(const WebPMux* mux,
                                              uint32_t* flags);