Merge pull request #3714 from Kelimion/png_cleanup

PNG cleanup

core/image/common.odin

@@ -1259,6 +1259,40 @@ apply_palette_rgba :: proc(img: ^Image, palette: [256]RGBA_Pixel, allocator := c
 }
 apply_palette :: proc{apply_palette_rgb, apply_palette_rgba}
 
+blend_single_channel :: #force_inline proc(fg, alpha, bg: $T) -> (res: T) where T == u8 || T == u16 {
+	MAX :: 256 when T == u8 else 65536
+
+	c := u32(fg) * (MAX - u32(alpha)) + u32(bg) * (1 + u32(alpha))
+	return T(c & (MAX - 1))
+}
+
+blend_pixel :: #force_inline proc(fg: [$N]$T, alpha: T, bg: [N]T) -> (res: [N]T) where (T == u8 || T == u16), N >= 1 && N <= 4 {
+	MAX :: 256 when T == u8 else 65536
+
+	when N == 1 {
+		r := u32(fg.r) * (MAX - u32(alpha)) + u32(bg.r) * (1 + u32(alpha))
+		return {T(r & (MAX - 1))}
+	}
+	when N == 2 {
+		r := u32(fg.r) * (MAX - u32(alpha)) + u32(bg.r) * (1 + u32(alpha))
+		g := u32(fg.g) * (MAX - u32(alpha)) + u32(bg.g) * (1 + u32(alpha))
+		return {T(r & (MAX - 1)), T(g & (MAX - 1))}
+	}
+	when N == 3 || N == 4 {
+		r := u32(fg.r) * (MAX - u32(alpha)) + u32(bg.r) * (1 + u32(alpha))
+		g := u32(fg.g) * (MAX - u32(alpha)) + u32(bg.g) * (1 + u32(alpha))
+		b := u32(fg.b) * (MAX - u32(alpha)) + u32(bg.b) * (1 + u32(alpha))
+
+		when N == 3 {
+			return {T(r & (MAX - 1)), T(g & (MAX - 1)), T(b & (MAX - 1))}
+		} else {
+			return {T(r & (MAX - 1)), T(g & (MAX - 1)), T(b & (MAX - 1)), MAX - 1}
+		}
+	}
+	unreachable()
+}
+blend :: proc{blend_single_channel, blend_pixel}
+
 
 // Replicates grayscale values into RGB(A) 8- or 16-bit images as appropriate.
 // Returns early with `false` if already an RGB(A) image.
@@ -1371,4 +1405,4 @@ write_bytes :: proc(buf: ^bytes.Buffer, data: []u8) -> (err: compress.General_Er
 		return .Resize_Failed
 	}
 	return nil
-}
+}

core/image/png/png.odin

@@ -597,7 +597,7 @@ load_from_context :: proc(ctx: ^$C, options := Options{}, allocator := context.a
 				dsc   := depth_scale_table
 				scale := dsc[info.header.bit_depth]
 				if scale != 1 {
-					key := mem.slice_data_cast([]u16be, c.data)[0] * u16be(scale)
+					key := (^u16be)(raw_data(c.data))^ * u16be(scale)
 					c.data = []u8{0, u8(key & 255)}
 				}
 			}
@@ -735,59 +735,48 @@ load_from_context :: proc(ctx: ^$C, options := Options{}, allocator := context.a
 			return {}, .Unable_To_Allocate_Or_Resize
 		}
 
-		i := 0; j := 0
-
 		// If we don't have transparency or drop it without applying it, we can do this:
 		if (!seen_trns || (seen_trns && .alpha_drop_if_present in options && .alpha_premultiply not_in options)) && .alpha_add_if_missing not_in options {
-			for h := 0; h < int(img.height); h += 1 {
-				for w := 0; w < int(img.width);  w += 1 {
-					c := _plte.entries[temp.buf[i]]
-					t.buf[j  ] = c.r
-					t.buf[j+1] = c.g
-					t.buf[j+2] = c.b
-					i += 1; j += 3
-				}
+			output := mem.slice_data_cast([]image.RGB_Pixel, t.buf[:])
+			for pal_idx, idx in temp.buf {
+				output[idx] = _plte.entries[pal_idx]
 			}
 		} else if add_alpha || .alpha_drop_if_present in options {
-			bg := [3]f32{0, 0, 0}
+			bg := PLTE_Entry{0, 0, 0}
 			if premultiply && seen_bkgd {
 				c16 := img.background.([3]u16)
-				bg = [3]f32{f32(c16.r), f32(c16.g), f32(c16.b)}
+				bg = {u8(c16.r), u8(c16.g), u8(c16.b)}
 			}
 
 			no_alpha := (.alpha_drop_if_present in options || premultiply) && .alpha_add_if_missing not_in options
 			blend_background := seen_bkgd && .blend_background in options
 
-			for h := 0; h < int(img.height); h += 1 {
-				for w := 0; w < int(img.width);  w += 1 {
-					index := temp.buf[i]
+			if no_alpha {
+				output := mem.slice_data_cast([]image.RGB_Pixel, t.buf[:])
+				for orig, idx in temp.buf {
+					c := _plte.entries[orig]
+					a := int(orig) < len(trns.data) ? trns.data[orig] : 255
 
-					c     := _plte.entries[index]
-					a     := int(index) < len(trns.data) ? trns.data[index] : 255
-					alpha := f32(a) / 255.0
+					if blend_background {
+						output[idx] = image.blend(c, a, bg)
+					} else if premultiply {
+						output[idx] = image.blend(PLTE_Entry{}, a, c)
+					}
+				}
+			} else {
+				output := mem.slice_data_cast([]image.RGBA_Pixel, t.buf[:])
+				for orig, idx in temp.buf {
+					c := _plte.entries[orig]
+					a := int(orig) < len(trns.data) ? trns.data[orig] : 255
 
 					if blend_background {
-						c.r = u8((1.0 - alpha) * bg[0] + f32(c.r) * alpha)
-						c.g = u8((1.0 - alpha) * bg[1] + f32(c.g) * alpha)
-						c.b = u8((1.0 - alpha) * bg[2] + f32(c.b) * alpha)
+						c = image.blend(c, a, bg)
 						a = 255
 					} else if premultiply {
-						c.r = u8(f32(c.r) * alpha)
-						c.g = u8(f32(c.g) * alpha)
-						c.b = u8(f32(c.b) * alpha)
+						c = image.blend(PLTE_Entry{}, a, c)
 					}
 
-					t.buf[j  ] = c.r
-					t.buf[j+1] = c.g
-					t.buf[j+2] = c.b
-					i += 1
-
-					if no_alpha {
-						j += 3
-					} else {
-						t.buf[j+3] = u8(a)
-						j += 4
-					}
+					output[idx] = {c.r, c.g, c.b, u8(a)}
 				}
 			}
 		} else {
@@ -1015,8 +1004,8 @@ load_from_context :: proc(ctx: ^$C, options := Options{}, allocator := context.a
 			return {}, .Unable_To_Allocate_Or_Resize
 		}
 
-		p := mem.slice_data_cast([]u8, temp.buf[:])
-		o := mem.slice_data_cast([]u8, t.buf[:])
+		p := temp.buf[:]
+		o := t.buf[:]
 
 		switch raw_image_channels {
 		case 1:
@@ -1627,7 +1616,6 @@ defilter :: proc(img: ^Image, filter_bytes: ^bytes.Buffer, header: ^image.PNG_IH
 	return nil
 }
 
-
 @(init, private)
 _register :: proc() {
 	image.register(.PNG, load_from_bytes, destroy)

tests/core/image/test_core_image.odin

@@ -1479,7 +1479,6 @@ run_png_suite :: proc(t: ^testing.T, suite: []Test) {
 
 				png_hash := hash.crc32(pixels)
 				testing.expectf(t, test.hash == png_hash, "%v test %v hash is %08x, expected %08x with %v", file.file, count, png_hash, test.hash, test.options)
-
 				passed &= test.hash == png_hash
 
 				if passed {
@@ -2358,4 +2357,40 @@ run_bmp_suite :: proc(t: ^testing.T, suite: []Test) {
 		}
 	}
 	return
+}
+
+@test
+will_it_blend :: proc(t: ^testing.T) {
+	Pixel    :: image.RGB_Pixel
+	Pixel_16 :: image.RGB_Pixel_16
+
+	{
+		bg := Pixel{255, 255,   0}
+		fg := Pixel{  0,   0, 255}
+
+		for a in 0..=255 {
+			blended := Pixel{
+				image.blend(fg.r, u8(a), bg.r),
+				image.blend(fg.g, u8(a), bg.g),
+				image.blend(fg.b, u8(a), bg.b),
+			}
+			testing.expectf(t, blended.r == bg.r - u8(a),    "Expected blend(%v, %3d, %v) = %v, got %v", fg.r, a, bg.r, bg.r - u8(a), blended.r)
+			testing.expectf(t, blended.b == 255 - blended.r, "Expected blend(%v, %3d, %v) = %v, got %v", fg.b, a, bg.b, 255 - blended.r, blended.b)
+		}
+	}
+
+	{
+		bg := Pixel_16{65535, 65535,     0}
+		fg := Pixel_16{    0,     0, 65535}
+
+		for a in 0..=65535 {
+			blended := Pixel_16{
+				image.blend(fg.r, u16(a), bg.r),
+				image.blend(fg.g, u16(a), bg.g),
+				image.blend(fg.b, u16(a), bg.b),
+			}
+			testing.expectf(t, blended.r == bg.r - u16(a),     "Expected blend(%v, %3d, %v) = %v, got %v", fg.r, a, bg.r, bg.r - u16(a), blended.r)
+			testing.expectf(t, blended.b == 65535 - blended.r, "Expected blend(%v, %3d, %v) = %v, got %v", fg.b, a, bg.b, 65535 - blended.r, blended.b)
+		}
+	}
 }

tests/core/normal.odin

@@ -20,7 +20,6 @@ download_assets :: proc() {
 @(require) import "encoding/varint"
 @(require) import "encoding/xml"
 @(require) import "fmt"
-@(require) import "image"
 @(require) import "math"
 @(require) import "math/big"
 @(require) import "math/linalg/glsl"

tests/core/speed.odin

@@ -3,3 +3,4 @@ package tests_core
 
 @(require) import "crypto"
 @(require) import "hash"
+@(require) import "image"