per-row opaque check

experiments/benchmark_cairo_draw.nim

@@ -1,4 +1,4 @@
-import benchy, cairo, pixie, pixie/blends
+import benchy, cairo, pixie, pixie/blends, pixie/internal
 
 when defined(amd64) and not defined(pixieNoSimd):
   import nimsimd/sse2
@@ -7,10 +7,8 @@ when defined(release):
   {.push checks: off.}
 
 proc drawBasic(backdrop, source: Image) =
-  let sourceIsOpaque = source.isOpaque()
-
   for y in 0 ..< min(backdrop.height, source.height):
-    if sourceIsOpaque:
+    if isOpaque(source.data, source.dataIndex(0, y), source.width):
       copyMem(
         backdrop.data[backdrop.dataIndex(0, y)].addr,
         source.data[source.dataIndex(0, y)].addr,

src/pixie/images.nim

@@ -182,29 +182,7 @@ proc isTransparent*(image: Image): bool {.raises: [].} =
 
 proc isOpaque*(image: Image): bool {.raises: [].} =
   ## Checks if the entire image is opaque (alpha values are all 255).
-  result = true
-
-  var i: int
-  when defined(amd64) and not defined(pixieNoSimd):
-    let
-      vec255 = mm_set1_epi32(cast[int32](uint32.high))
-      colorMask = mm_set1_epi32(cast[int32]([255.uint8, 255, 255, 0]))
-    for _ in 0 ..< image.data.len div 16:
-      let
-        values0 = mm_loadu_si128(image.data[i + 0].addr)
-        values1 = mm_loadu_si128(image.data[i + 4].addr)
-        values2 = mm_loadu_si128(image.data[i + 8].addr)
-        values3 = mm_loadu_si128(image.data[i + 12].addr)
-        values01 = mm_and_si128(values0, values1)
-        values23 = mm_and_si128(values2, values3)
-        values = mm_or_si128(mm_and_si128(values01, values23), colorMask)
-      if mm_movemask_epi8(mm_cmpeq_epi8(values, vec255)) != 0xffff:
-        return false
-      i += 16
-
-  for j in i ..< image.data.len:
-    if image.data[j].a != 255:
-      return false
+  isOpaque(image.data, 0, image.data.len)
 
 proc flipHorizontal*(image: Image) {.raises: [].} =
   ## Flips the image around the Y axis.
@@ -789,9 +767,6 @@ proc drawUber(
     if yMin > 0 and yMin < a.height:
       zeroMem(a.data[0].addr, 4 * yMin * a.width)
 
-  when type(a) is Image and type(b) is Image:
-    let opaqueFastPath = blendMode in {bmNormal, bmOverwrite} and b.isOpaque()
-
   for y in yMin ..< yMax:
     # Determine where we should start and stop drawing in the x dimension
     var
@@ -852,7 +827,8 @@ proc drawUber(
       var x = xStart
       if not hasRotation:
         when type(a) is Image and type(b) is Image:
-          if opaqueFastPath:
+          if blendMode in {bmNormal, bmOverwrite} and
+            isOpaque(b.data, b.dataIndex(xStart, y), xStop - xStart):
             let
               srcPos = p + dx * x.float32 + dy * y.float32
               sx = srcPos.x.int

src/pixie/internal.nim

@@ -96,6 +96,31 @@ proc toPremultipliedAlpha*(data: var seq[ColorRGBA | ColorRGBX]) {.raises: [].}
       c.b = ((c.b.uint32 * c.a.uint32) div 255).uint8
       data[j] = c
 
+proc isOpaque*(data: var seq[ColorRGBX], start, len: int): bool =
+  result = true
+
+  var i: int
+  when defined(amd64) and not defined(pixieNoSimd):
+    let
+      vec255 = mm_set1_epi32(cast[int32](uint32.high))
+      colorMask = mm_set1_epi32(cast[int32]([255.uint8, 255, 255, 0]))
+    for _ in 0 ..< len div 16:
+      let
+        values0 = mm_loadu_si128(data[i + 0].addr)
+        values1 = mm_loadu_si128(data[i + 4].addr)
+        values2 = mm_loadu_si128(data[i + 8].addr)
+        values3 = mm_loadu_si128(data[i + 12].addr)
+        values01 = mm_and_si128(values0, values1)
+        values23 = mm_and_si128(values2, values3)
+        values = mm_or_si128(mm_and_si128(values01, values23), colorMask)
+      if mm_movemask_epi8(mm_cmpeq_epi8(values, vec255)) != 0xffff:
+        return false
+      i += 16
+
+  for j in i ..< len:
+    if data[j].a != 255:
+      return false
+
 when defined(amd64) and not defined(pixieNoSimd):
   proc packAlphaValues*(v: M128i): M128i {.inline, raises: [].} =
     ## Shuffle the alpha values for these 4 colors to the first 4 bytes