commit ce98801bbb5ac251b374f8b565445add43017aaa
author Mike Klein <mtklein@chromium.org> Fri Jul 21 13:11:37 2017 -0400
committer Skia Commit-Bot <skia-commit-bot@chromium.org> Fri Jul 21 17:47:24 2017 +0000
tree 28cb9dbdc430844c78962b12d64353d3d82f77c6
parent 7634330c98356548cacd63e805688d20579fd1f5

when encoding PNG, don't assume F16 values are in range

I believe this will fix this batch of broken colorImages:

   https://gold.skia.org/search?blame=e23e55ef33358b2f6f98fc9cb795c71397c01618&fdiffmax=-1&fref=false&frgbamax=255&frgbamin=0&head=true&include=false&limit=50&match=gamma_correct&match=name&metric=combined&neg=false&offset=0&pos=false&query=source_type%3DcolorImage&sort=desc&unt=true

Depending on the instruction set, clamping to logical [0,1] may be
implicit or not as we work our way down to bytes.  I think that's why
these broken images are not more widespread on the bots.

Change-Id: Ie9bb937864bf6954301d76d9921a2d3029d12c9a
Reviewed-on: https://skia-review.googlesource.com/25742
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

src/images/SkImageEncoderFns.h

diff --git a/src/images/SkImageEncoderFns.h b/src/images/SkImageEncoderFns.h
index eb6ce8b..a17b30b 100644
--- a/src/images/SkImageEncoderFns.h
+++ b/src/images/SkImageEncoderFns.h
@@ -265,6 +265,8 @@
                        dst_ctx = { (void*)dst, 0 };
     SkRasterPipeline_<256> p;
     p.append(SkRasterPipeline::load_f16, &src_ctx);
+    p.append(SkRasterPipeline::clamp_0);  // F16 values may be out of [0,1] range, so clamp.
+    p.append(SkRasterPipeline::clamp_1);
     p.append(SkRasterPipeline::to_srgb);
     p.append(SkRasterPipeline::store_u16_be, &dst_ctx);
     p.run(0,0, width,1);
@@ -280,6 +282,8 @@
     SkRasterPipeline_<256> p;
     p.append(SkRasterPipeline::load_f16, &src_ctx);
     p.append(SkRasterPipeline::unpremul);
+    p.append(SkRasterPipeline::clamp_0);  // F16 values may be out of [0,1] range, so clamp.
+    p.append(SkRasterPipeline::clamp_1);
     p.append(SkRasterPipeline::to_srgb);
     p.append(SkRasterPipeline::store_u16_be, &dst_ctx);
     p.run(0,0, width,1);
@@ -295,6 +299,8 @@
                        dst_ctx = { (void*)dst, 0 };
     SkRasterPipeline_<256> p;
     p.append(SkRasterPipeline::load_f16, &src_ctx);
+    p.append(SkRasterPipeline::clamp_0);  // F16 values may be out of [0,1] range, so clamp.
+    p.append(SkRasterPipeline::clamp_1);
     p.append(SkRasterPipeline::to_srgb);
     p.append(SkRasterPipeline::store_8888, &dst_ctx);
     p.run(0,0, width,1);
@@ -311,6 +317,8 @@
     SkRasterPipeline_<256> p;
     p.append(SkRasterPipeline::load_f16, &src_ctx);
     p.append(SkRasterPipeline::unpremul);
+    p.append(SkRasterPipeline::clamp_0);  // F16 values may be out of [0,1] range, so clamp.
+    p.append(SkRasterPipeline::clamp_1);
     p.append(SkRasterPipeline::to_srgb);
     p.append(SkRasterPipeline::store_8888, &dst_ctx);
     p.run(0,0, width,1);
@@ -325,6 +333,8 @@
                        dst_ctx = { (void*)dst, 0 };
     SkRasterPipeline_<256> p;
     p.append(SkRasterPipeline::load_f16, &src_ctx);
+    p.append(SkRasterPipeline::clamp_0);  // F16 values may be out of [0,1] range, so clamp.
+    p.append(SkRasterPipeline::clamp_1);
     p.append(SkRasterPipeline::premul);
     p.append(SkRasterPipeline::to_srgb);
     p.append(SkRasterPipeline::store_8888, &dst_ctx);