Move DM png code to picture_utils, for use by other tools.

dm/DM.cpp

Index: dm/DM.cpp
diff --git a/dm/DM.cpp b/dm/DM.cpp
index ecf231ed63b73bc378b36b6f7096765cb1035228..58cb773e032a5f1bb9182dc3db4b0b08043fb8c6 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -17,6 +17,7 @@
 #include "SkColorPriv.h"
 #include "SkCommonFlags.h"
 #include "SkCommonFlagsConfig.h"
+#include "SkData.h"
 #include "SkFontMgr.h"
 #include "SkGraphics.h"
 #include "SkHalf.h"
@@ -30,6 +31,7 @@
 #include "SkThreadUtils.h"
 #include "Test.h"
 #include "Timer.h"
+#include "picture_utils.h"
 #include "sk_tool_utils.h"
 
 #ifdef SK_PDF_IMAGE_STATS
@@ -924,72 +926,12 @@ static void gather_sinks() {
 static bool dump_png(SkBitmap bitmap, const char* path, const char* md5) {
     const int w = bitmap.width(),
               h = bitmap.height();
-    // PNG wants unpremultiplied 8-bit RGBA pixels (16-bit could work fine too).
-    // We leave the gamma of these bytes unspecified, to continue the status quo,
-    // which we think generally is to interpret them as sRGB.
-
-    SkAutoTMalloc<uint32_t> rgba(w*h);
-
-    if (bitmap.  colorType() ==  kN32_SkColorType &&
-        bitmap.profileType() == kSRGB_SkColorProfileType) {
-        // These are premul sRGB 8-bit pixels in SkPMColor order.
-        // We want unpremul sRGB 8-bit pixels in RGBA order.  We'll get there via floats.
-        bitmap.lockPixels();
-        auto px = (const uint32_t*)bitmap.getPixels();
-        if (!px) {
-            return false;
-        }
-        for (int i = 0; i < w*h; i++) {
-            Sk4f fs = Sk4f_fromS32(px[i]);         // Convert up to linear floats.
-        #if defined(SK_PMCOLOR_IS_BGRA)
-            fs = SkNx_shuffle<2,1,0,3>(fs);        // Shuffle to RGBA, if not there already.
-        #endif
-            float invA = 1.0f / fs[3];
-            fs = fs * Sk4f(invA, invA, invA, 1);   // Unpremultiply.
-            rgba[i] = Sk4f_toS32(fs);              // Pack down to sRGB bytes.
-        }
-
-    } else if (bitmap.colorType() == kRGBA_F16_SkColorType) {
-        // These are premul linear half-float pixels in RGBA order.
-        // We want unpremul sRGB 8-bit pixels in RGBA order.  We'll get there via floats.
-        bitmap.lockPixels();
-        auto px = (const uint64_t*)bitmap.getPixels();
-        if (!px) {
-            return false;
-        }
-        for (int i = 0; i < w*h; i++) {
-            // Convert up to linear floats.
-            Sk4f fs(SkHalfToFloat(static_cast<SkHalf>(px[i] >> (0 * 16))),
-                    SkHalfToFloat(static_cast<SkHalf>(px[i] >> (1 * 16))),
-                    SkHalfToFloat(static_cast<SkHalf>(px[i] >> (2 * 16))),
-                    SkHalfToFloat(static_cast<SkHalf>(px[i] >> (3 * 16))));
-            fs = Sk4f::Max(0.0f, Sk4f::Min(fs, 1.0f));  // Clamp
-            float invA = 1.0f / fs[3];
-            fs = fs * Sk4f(invA, invA, invA, 1);  // Unpremultiply.
-            rgba[i] = Sk4f_toS32(fs);             // Pack down to sRGB bytes.
-        }
 
-
-    } else {
-        // We "should" gamma correct in here but we don't.
-        // We want Gold to show exactly what our clients are seeing, broken gamma.
-
-        // Convert smaller formats up to premul linear 8-bit (in SkPMColor order).
-        if (bitmap.colorType() != kN32_SkColorType) {
-            SkBitmap n32;
-            if (!bitmap.copyTo(&n32, kN32_SkColorType)) {
-                return false;
-            }
-            bitmap = n32;
-        }
-
-        // Convert premul linear 8-bit to unpremul linear 8-bit RGBA.
-        if (!bitmap.readPixels(SkImageInfo::Make(w,h, kRGBA_8888_SkColorType,
-                                                      kUnpremul_SkAlphaType),
-                               rgba, 4*w, 0,0)) {
-            return false;
-        }
+    sk_sp<SkData> encodedBitmap = sk_tools::encode_bitmap_for_png(bitmap);
+    if (encodedBitmap.get() == nullptr) {
+        return false;
     }
+    uint32_t* rgba = static_cast<uint32_t*>(encodedBitmap.get()->writable_data());
 
     // We don't need bitmap anymore.  Might as well drop our ref.
     bitmap.reset();
@@ -1036,7 +978,7 @@ static bool dump_png(SkBitmap bitmap, const char* path, const char* md5) {
                  PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
     png_write_info(png, info);
     for (int j = 0; j < h; j++) {
-        png_bytep row = (png_bytep)(rgba.get() + w*j);
+        png_bytep row = (png_bytep)(rgba + w*j);
         png_write_rows(png, &row, 1);
     }
     png_write_end(png, info);