Display JPGs in Viewer with Split Screen and ColorSpaceXform

tools/viewer/ImageSlide.cpp

+/*
+* Copyright 2016 Google Inc.
+*
+* Use of this source code is governed by a BSD-style license that can be
+* found in the LICENSE file.
+*/
+
+#include "ImageSlide.h"
+
+#include "SkBitmap.h"
+#include "SkCodec.h"
+#include "SkColorSpaceXform.h"
+#include "SkColorSpace.h"
+#include "SkCanvas.h"
+#include "SkData.h"
+#include "SkImage.h"
+#include "SkMetaData.h"
+
+ImageSlide::ImageSlide(const SkString& name, const SkString& path) : fPath(path) {
+    fName = name;
+}
+
+SkISize ImageSlide::getDimensions() const {
+    return fImage ? fImage->dimensions() : SkISize::Make(0, 0);
+}
+
+void ImageSlide::draw(SkCanvas* canvas) {
+    if (canvas->getMetaData().hasBool(kImageColorXformMetaData, true)) {
+        canvas->drawBitmap(fXformedBitmap, 0, 0);
+    } else {
+        // canvas->drawImage(fImage.get(), 0, 0); // drawImage is currently having bugs

[msarett, 2016/06/13 14:56:26]

I would say go ahead and file a bug.  That way the comment can say something
like:

// skbug.com/XXXX
// drawImage() and drawBitmap() behave differently in sRGB mode.

[liyuqian, 2016/06/13 16:10:40]

Done.

+        canvas->drawBitmap(fOriginalBitmap, 0, 0);
+    }
+}
+
+void ImageSlide::load() {
+    sk_sp<SkData> encoded(SkData::NewFromFileName(fPath.c_str()));

[msarett, 2016/06/13 14:56:26]

nit:

sk_sp<SkData> encoded = SkData::NewFromFileName(fPath.c_str());

[liyuqian, 2016/06/13 16:10:40]

no viable conversion from 'SkData *' to 'sk_sp<SkData>'

[msarett, 2016/06/13 16:57:35]

Ahh sorry!  You should use SkData::MakeFromFileName().

[liyuqian, 2016/06/13 19:02:29]

Done.

+    fImage = SkImage::MakeFromEncoded(encoded);
+    fImage->asLegacyBitmap(&fOriginalBitmap, SkImage::kRO_LegacyBitmapMode);
+
+    SkAutoTDelete<SkCodec> codec(SkCodec::NewFromData(encoded.get()));
+    sk_sp<SkColorSpace> srcSpace = sk_ref_sp(codec->getColorSpace());
+    sk_sp<SkColorSpace> dstSpace = SkColorSpace::NewNamed(SkColorSpace::kAdobeRGB_Named);
+    std::unique_ptr<SkColorSpaceXform> xform = SkColorSpaceXform::New(srcSpace, dstSpace);
+    fImage->asLegacyBitmap(&fXformedBitmap, SkImage::kRW_LegacyBitmapMode);

[msarett, 2016/06/13 14:56:26]

nit: I believe that MakeFromEncoded() is lazy, meaning that it won't decode the
image (it will just hold the encoded data).  asLegacyBitmap() will need to
decode the image (since bitmaps always have pixels).  By calling
asLegacyBitmap() twice, we will actually decode the image twice, which is a bit
inefficient.

Could we instead create fXformedBitmap as a (deep) copy of fOriginalBitmap
before modifying the pixels?

[liyuqian, 2016/06/13 16:10:40]

Done.

+    uint32_t* row = (uint32_t*) fXformedBitmap.getPixels();
+    for (int y = 0; y < fXformedBitmap.height(); y++) {
+        xform->xform_RGBA_8888(row, row, fXformedBitmap.width());
+        row = SkTAddOffset<uint32_t>(row, fXformedBitmap.rowBytes());
+    }
+}
+
+void ImageSlide::unload() {
+    fImage.reset(nullptr);
+}