[core] Simplify and fix sprite atlas coordinate calculations

* Always return image metrics exclusive of padding
* Work with integer coordinates whenever possible
* Eliminate redundant SpriteAtlasElement members
* Fix asymmetric re-padding in getIconQuad when pixelRatio != 1
* Add explanatory comments

1 files changed, 31 insertions, 56 deletions

diff --git a/test/sprite/sprite_atlas.test.cpp b/test/sprite/sprite_atlas.test.cpp
index f6953e61f7..c673c5ca0e 100644
--- a/test/sprite/sprite_atlas.test.cpp
+++ b/test/sprite/sprite_atlas.test.cpp
@@ -26,34 +26,21 @@ TEST(SpriteAtlas, Basic) {
         atlas.addImage(image->impl);
     }
 
-    EXPECT_EQ(1.0f, atlas.getPixelRatio());
-    EXPECT_EQ(63u, atlas.getSize().width);
-    EXPECT_EQ(112u, atlas.getSize().height);
+    EXPECT_EQ(63u, atlas.getPixelSize().width);
+    EXPECT_EQ(112u, atlas.getPixelSize().height);
 
     auto metro = *atlas.getIcon("metro");
-    float imagePixelRatio = metro.relativePixelRatio * atlas.getPixelRatio();
-    EXPECT_EQ(0, metro.pos.x);
-    EXPECT_EQ(0, metro.pos.y);
-    EXPECT_EQ(20, metro.pos.w);
-    EXPECT_EQ(20, metro.pos.h);
-    EXPECT_EQ(18, metro.size[0]);
-    EXPECT_EQ(18, metro.size[1]);
-    EXPECT_EQ(18u, metro.size[0] * imagePixelRatio);
-    EXPECT_EQ(18u, metro.size[1] * imagePixelRatio);
-    EXPECT_EQ(1.0f, imagePixelRatio);
-
+    EXPECT_EQ(1, metro.tl()[0]);
+    EXPECT_EQ(1, metro.tl()[1]);
+    EXPECT_EQ(19, metro.br()[0]);
+    EXPECT_EQ(19, metro.br()[1]);
+    EXPECT_EQ(18, metro.displaySize()[0]);
+    EXPECT_EQ(18, metro.displaySize()[1]);
+    EXPECT_EQ(1.0f, metro.pixelRatio);
 
     EXPECT_EQ(63u, atlas.getAtlasImage().size.width);
     EXPECT_EQ(112u, atlas.getAtlasImage().size.height);
 
-    auto pos = *atlas.getIcon("metro");
-    EXPECT_DOUBLE_EQ(18, pos.size[0]);
-    EXPECT_DOUBLE_EQ(18, pos.size[1]);
-    EXPECT_DOUBLE_EQ(1.0f / 63, pos.tl[0]);
-    EXPECT_DOUBLE_EQ(1.0f / 112, pos.tl[1]);
-    EXPECT_DOUBLE_EQ(19.0f / 63, pos.br[0]);
-    EXPECT_DOUBLE_EQ(19.0f / 112, pos.br[1]);
-
     auto missing = atlas.getIcon("doesnotexist");
     EXPECT_FALSE(missing);
 
@@ -66,10 +53,10 @@ TEST(SpriteAtlas, Basic) {
 
     // Different wrapping mode produces different image.
     auto metro2 = *atlas.getPattern("metro");
-    EXPECT_EQ(20, metro2.pos.x);
-    EXPECT_EQ(0, metro2.pos.y);
-    EXPECT_EQ(20, metro2.pos.w);
-    EXPECT_EQ(20, metro2.pos.h);
+    EXPECT_EQ(21, metro2.tl()[0]);
+    EXPECT_EQ(1, metro2.tl()[1]);
+    EXPECT_EQ(39, metro2.br()[0]);
+    EXPECT_EQ(19, metro2.br()[1]);
 
     test::checkImage("test/fixtures/sprite_atlas/basic", atlas.getAtlasImage());
 }
@@ -83,25 +70,17 @@ TEST(SpriteAtlas, Size) {
         atlas.addImage(image->impl);
     }
 
-    EXPECT_DOUBLE_EQ(1.4f, atlas.getPixelRatio());
-    EXPECT_EQ(63u, atlas.getSize().width);
-    EXPECT_EQ(112u, atlas.getSize().height);
+    EXPECT_EQ(89u, atlas.getPixelSize().width);
+    EXPECT_EQ(157u, atlas.getPixelSize().height);
 
     auto metro = *atlas.getIcon("metro");
-    float imagePixelRatio = metro.relativePixelRatio * atlas.getPixelRatio();
-    EXPECT_EQ(0, metro.pos.x);
-    EXPECT_EQ(0, metro.pos.y);
-    EXPECT_EQ(15, metro.pos.w);
-    EXPECT_EQ(15, metro.pos.h);
-    EXPECT_EQ(18, metro.size[0]);
-    EXPECT_EQ(18, metro.size[1]);
-    EXPECT_EQ(18u, metro.size[0] * imagePixelRatio);
-    EXPECT_EQ(18u, metro.size[1] * imagePixelRatio);
-    EXPECT_EQ(1.0f, imagePixelRatio);
-
-    // Now the image was created lazily.
-    EXPECT_EQ(89u, atlas.getAtlasImage().size.width);
-    EXPECT_EQ(157u, atlas.getAtlasImage().size.height);
+    EXPECT_EQ(1, metro.tl()[0]);
+    EXPECT_EQ(1, metro.tl()[1]);
+    EXPECT_EQ(19, metro.br()[0]);
+    EXPECT_EQ(19, metro.br()[1]);
+    EXPECT_EQ(18, metro.displaySize()[0]);
+    EXPECT_EQ(18, metro.displaySize()[1]);
+    EXPECT_EQ(1.0f, metro.pixelRatio);
 
     test::checkImage("test/fixtures/sprite_atlas/size", atlas.getAtlasImage());
 }
@@ -109,22 +88,18 @@ TEST(SpriteAtlas, Size) {
 TEST(SpriteAtlas, Updates) {
     SpriteAtlas atlas({ 32, 32 }, 1);
 
-    EXPECT_EQ(1.0f, atlas.getPixelRatio());
-    EXPECT_EQ(32u, atlas.getSize().width);
-    EXPECT_EQ(32u, atlas.getSize().height);
+    EXPECT_EQ(32u, atlas.getPixelSize().width);
+    EXPECT_EQ(32u, atlas.getPixelSize().height);
 
     atlas.addImage(makeMutable<style::Image::Impl>("one", PremultipliedImage({ 16, 12 }), 1));
     auto one = *atlas.getIcon("one");
-    float imagePixelRatio = one.relativePixelRatio * atlas.getPixelRatio();
-    EXPECT_EQ(0, one.pos.x);
-    EXPECT_EQ(0, one.pos.y);
-    EXPECT_EQ(18, one.pos.w);
-    EXPECT_EQ(14, one.pos.h);
-    EXPECT_EQ(16, one.size[0]);
-    EXPECT_EQ(12, one.size[1]);
-    EXPECT_EQ(16u, one.size[0] * imagePixelRatio);
-    EXPECT_EQ(12u, one.size[1] * imagePixelRatio);
-    EXPECT_EQ(1.0f, imagePixelRatio);
+    EXPECT_EQ(1, one.tl()[0]);
+    EXPECT_EQ(1, one.tl()[1]);
+    EXPECT_EQ(17, one.br()[0]);
+    EXPECT_EQ(13, one.br()[1]);
+    EXPECT_EQ(16, one.displaySize()[0]);
+    EXPECT_EQ(12, one.displaySize()[1]);
+    EXPECT_EQ(1.0f, one.pixelRatio);
 
     // Now the image was created lazily.
     EXPECT_EQ(32u, atlas.getAtlasImage().size.width);