add peekPixels to SkCanvas and SkSurface

clone of https://codereview.chromium.org/159723006/

Review URL: https://codereview.chromium.org/161733002

git-svn-id: http://skia.googlecode.com/svn/trunk@13427 2bbb7eff-a529-9590-31e7-b0007b416f81

4 files changed, 74 insertions, 0 deletions

diff --git a/src/core/SkBitmapDevice.cpp b/src/core/SkBitmapDevice.cpp
index 9dde6e172e..374bef98c1 100644
--- a/src/core/SkBitmapDevice.cpp
+++ b/src/core/SkBitmapDevice.cpp
@@ -54,6 +54,10 @@ SkBitmapDevice::SkBitmapDevice(SkBitmap::Config config, int width, int height, b
 SkBitmapDevice::~SkBitmapDevice() {
 }
 
+SkImageInfo SkBitmapDevice::imageInfo() const {
+    return fBitmap.info();
+}
+
 void SkBitmapDevice::replaceBitmapBackendForRasterSurface(const SkBitmap& bm) {
     SkASSERT(bm.width() == fBitmap.width());
     SkASSERT(bm.height() == fBitmap.height());
@@ -386,6 +390,16 @@ SkSurface* SkBitmapDevice::newSurface(const SkImageInfo& info) {
     return SkSurface::NewRaster(info);
 }
 
+const void* SkBitmapDevice::peekPixels(SkImageInfo* info, size_t* rowBytes) {
+    if (fBitmap.getPixels() && fBitmap.asImageInfo(info)) {
+        if (rowBytes) {
+            *rowBytes = fBitmap.rowBytes();
+        }
+        return fBitmap.getPixels();
+    }
+    return NULL;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 bool SkBitmapDevice::filterTextFlags(const SkPaint& paint, TextFlags* flags) {
diff --git a/src/core/SkCanvas.cpp b/src/core/SkCanvas.cpp
index ed8274dc5d..f5e91ffc43 100644
--- a/src/core/SkCanvas.cpp
+++ b/src/core/SkCanvas.cpp
@@ -992,6 +992,55 @@ SkSurface* SkCanvas::onNewSurface(const SkImageInfo& info) {
     return dev ? dev->newSurface(info) : NULL;
 }
 
+SkImageInfo SkCanvas::imageInfo() const {
+    SkBaseDevice* dev = this->getDevice();
+    if (dev) {
+        return dev->imageInfo();
+    } else {
+        // TODO: need a real unknown for alphatype it seems.
+        SkAlphaType unknownAlphaType = kIgnore_SkAlphaType;
+        return SkImageInfo::Make(0, 0, kUnknown_SkColorType, unknownAlphaType);
+    }
+}
+
+const void* SkCanvas::peekPixels(SkImageInfo* info, size_t* rowBytes) {
+    return this->onPeekPixels(info, rowBytes);
+}
+
+const void* SkCanvas::onPeekPixels(SkImageInfo* info, size_t* rowBytes) {
+    SkBaseDevice* dev = this->getDevice();
+    return dev ? dev->peekPixels(info, rowBytes) : NULL;
+}
+
+SkAutoROCanvasPixels::SkAutoROCanvasPixels(SkCanvas* canvas) {
+    fAddr = canvas->peekPixels(&fInfo, &fRowBytes);
+    if (NULL == fAddr) {
+        fInfo = canvas->imageInfo();
+        if (kUnknown_SkColorType == fInfo.colorType() ||
+            !fBitmap.allocPixels(fInfo))
+        {
+            return; // failure, fAddr is NULL
+        }
+        fBitmap.lockPixels();
+        if (!canvas->readPixels(&fBitmap, 0, 0)) {
+            return; // failure, fAddr is NULL
+        }
+        fAddr = fBitmap.getPixels();
+        fRowBytes = fBitmap.rowBytes();
+    }
+    SkASSERT(fAddr);    // success
+}
+
+bool SkAutoROCanvasPixels::asROBitmap(SkBitmap* bitmap) const {
+    if (fAddr) {
+        return bitmap->installPixels(fInfo, const_cast<void*>(fAddr), fRowBytes,
+                                     NULL, NULL);
+    } else {
+        bitmap->reset();
+        return false;
+    }
+}
+
 /////////////////////////////////////////////////////////////////////////////
 
 void SkCanvas::internalDrawBitmap(const SkBitmap& bitmap,
diff --git a/src/core/SkDevice.cpp b/src/core/SkDevice.cpp
index 9ce8b6b5df..364b106dd8 100644
--- a/src/core/SkDevice.cpp
+++ b/src/core/SkDevice.cpp
@@ -65,6 +65,12 @@ SkMetaData& SkBaseDevice::getMetaData() {
     return *fMetaData;
 }
 
+// TODO: should make this guy pure-virtual.
+SkImageInfo SkBaseDevice::imageInfo() const {
+    return SkImageInfo::Make(this->width(), this->height(),
+                             kUnknown_SkColorType, kIgnore_SkAlphaType);
+}
+
 const SkBitmap& SkBaseDevice::accessBitmap(bool changePixels) {
     const SkBitmap& bitmap = this->onAccessBitmap();
     if (changePixels) {
@@ -117,3 +123,5 @@ bool SkBaseDevice::readPixels(SkBitmap* bitmap, int x, int y,
 }
 
 SkSurface* SkBaseDevice::newSurface(const SkImageInfo&) { return NULL; }
+
+const void* SkBaseDevice::peekPixels(SkImageInfo*, size_t*) { return NULL; }
diff --git a/src/core/SkPictureRecord.h b/src/core/SkPictureRecord.h
index 0df120b31a..eaa5e73008 100644
--- a/src/core/SkPictureRecord.h
+++ b/src/core/SkPictureRecord.h
@@ -221,6 +221,9 @@ public:
 
 protected:
     virtual SkSurface* onNewSurface(const SkImageInfo&) SK_OVERRIDE;
+    const void* onPeekPixels(SkImageInfo*, size_t*) SK_OVERRIDE {
+        return NULL;
+    }
 
     // Return fontmetrics.fTop,fBottom in topbot[0,1], after they have been
     // tweaked by paint.computeFastBounds().