libimg: Improve support of transparent PNG images.

* Support grayscale images with alpha channel.
* Support rgb images with transparent color.
* Process 'tRNS' chunk (simple transparency).

Transparent png images were already supported for color type 6, which
is RGBA. Now indexed images (color type 3) can also have transparency
via 'tRNS' chunk data.

git-svn-id: svn://kolibrios.org@8449 a494cfbc-eb01-0410-851d-a64ba20cac60

programs/develop/libraries/libs-dev/libimg/convert.asm

@@ -633,6 +633,22 @@ proc img._.convert.bpp8a_to_bpp24 _src, _dst
 endp
 
 
+proc img._.convert.bpp8a_to_bpp32 _src, _dst
+        mov     ecx, [ebx + Image.Width]
+        imul    ecx, [ebx + Image.Height]
+    @@:
+        lodsw
+        shl     eax, 8
+        mov     al, ah
+        shl     eax, 8
+        mov     al, ah
+        stosd
+        dec     ecx
+        jnz     @b
+        ret
+endp
+
+
 img.convert.bpp8i.table:
         dd Image.bpp24, img._.convert.bpp8i_to_bpp24
         dd Image.bpp32, img._.convert.bpp8i_to_bpp32
@@ -665,6 +681,7 @@ img.convert.bpp4i.table:
         dd 0
 img.convert.bpp8a.table:
         dd Image.bpp24, img._.convert.bpp8a_to_bpp24
+        dd Image.bpp32, img._.convert.bpp8a_to_bpp32
         dd 0
 
 img.convert.table:

programs/develop/libraries/libs-dev/libimg/png/png.asm

@@ -56,12 +56,13 @@ img.decode.png:
 	xor	eax, eax	; .image = 0
 	pushad
 	mov	ebp, esp
-.localsize = 29*4
+.localsize = 30*4
 virtual at ebp - .localsize
 .width		dd	?
 .height		dd	?
 .bit_depth	dd	?
 .color_type	dd	?
+.transparent_color dd	?
 .bytes_per_pixel dd	?
 .scanline_len	dd	?
 .bits_per_pixel dd	?
@@ -158,6 +159,8 @@ end virtual
 	jz	.iend
 	cmp	eax, 'PLTE'
 	jz	.palette
+	cmp	eax, 'tRNS'
+	jz	.transparency
 ; unrecognized chunk, ignore
 	lea	esi, [esi+ecx+4]
 	pop	ecx
@@ -233,14 +236,17 @@ end virtual
 	add	eax, 7
 	shr	eax, 3
 	mov	[.bytes_per_pixel], eax
+	mov	[.transparent_color], 0
 ; allocate image
-	push	Image.bpp24
-	pop	eax
+	movi	eax, Image.bpp32
 	cmp	[.color_type], 2
 	jz	@f
 	mov	al, Image.bpp32
 	cmp	[.color_type], 6
 	jz	@f
+	mov	al, Image.bpp8a
+	cmp	[.color_type], 4
+	jz	@f
 	mov	al, Image.bpp8i
 @@:
 	stdcall	img.create, [.width], [.height], eax
@@ -288,11 +294,73 @@ end virtual
 	lodsd
 	dec	esi
 	bswap	eax
-	shr	eax, 8
+	mov     al, 0xff
+	ror	eax, 8
 	stosd
 	jmp	.next_chunk
+; convert 16 bit sample to 8 bit sample
+macro convert_16_to_8
+{
+local .l1,.l2
+	xor	ah, 0x80
+	js	.l1
+	cmp	al, ah
+	adc	al, 0
+	jmp	.l2
+.l1:
+	cmp	ah, al
+	sbb	al, 0
+.l2:
+}
+; tRNS chunk
+.transparency:
+	mov	eax, [.image]
+	test	eax, eax
+	jz	.invalid_chunk
+	cmp	[.color_type], 2	; rgb
+	jz	.transparency_rgb
+	cmp	[.color_type], 3	; indexed
+	jz	.transparency_indexed
+	add	esi, ecx
+	jmp	.next_chunk
+.transparency_rgb:
+	cmp	[.bit_depth], 16
+	jz	.transparency_rgb16
+	lodsw
+	shl	eax, 8
+	lodsw
+	shl	eax, 8
+	lodsw
+	mov	al, 0xff
+	ror	eax, 8
+	mov	[.transparent_color], eax
+	jmp	.next_chunk
+.transparency_rgb16:
+	lodsw
+	convert_16_to_8
+	shl	ax, 8
+	shl	eax, 8
+	lodsw
+	convert_16_to_8
+	shl	ax, 8
+	shl	eax, 8
+	lodsw
+	convert_16_to_8
+	shl	ax, 8
+	mov	al, 0xff
+	ror	eax, 8
+	mov	[.transparent_color], eax
+	jmp	.next_chunk
+.transparency_indexed:
+	mov	edi, [eax + Image.Palette]
+@@:
+	add	edi, 3
+	movsb
+	loop	@b
+	jmp	.next_chunk
 .idat:
-	jecxz	.next_chunk
+	test	ecx, ecx
+	jz	.next_chunk
 	cmp	[.idat_read], 0
 	jnz	@f
 	lodsb
@@ -654,22 +722,6 @@ macro init_block
 	init_block
 	lea	eax, [edi+eax*4]
 	push	eax
-
-; convert 16 bit sample to 8 bit sample
-macro convert_16_to_8
-{
-local .l1,.l2
-	xor	ah, 0x80
-	js	.l1
-	cmp	al, ah
-	adc	al, 0
-	jmp	.l2
-.l1:
-	cmp	ah, al
-	sbb	al, 0
-.l2:
-}
-
 .rgb_alpha2_16bit.innloop1:
 	push	edi
 	mov	ecx, ebx
@@ -872,20 +924,21 @@ local .l1
 	mov	[.i], ecx
 .rgb2.extloop:
 	init_block
-	lea	eax, [eax*3]
-	add	eax, edi
+	lea	eax, [edi+eax*4]
 	push	eax
 .rgb2.innloop1:
 	push	edi
 	mov	ecx, ebx
 .rgb2.innloop2:
-	mov	al, [esi+2]
-	mov	[edi], al
-	mov	al, [esi+1]
-	mov	[edi+1], al
-	mov	al, [esi]
-	mov	[edi+2], al
-	add	edi, 3
+	mov	eax, [esi]
+	bswap	eax
+	mov	al, 0xff
+	ror	eax, 8
+	cmp	eax, [.transparent_color]
+	jnz	@f
+	and	eax, 0x00ffffff
+@@:
+	stosd
 	dec	ecx
 	jnz	.rgb2.innloop2
 	pop	edi
@@ -947,7 +1000,6 @@ local .l1
 	ja	.rgb2_16bit
 	jmp	.convert_done
 .grayscale_alpha2:
-	call	.create_grayscale_palette
 	cmp	[.bit_depth], 16
 	jz	.grayscale_alpha2_16bit
 .grayscale_alpha2.next:
@@ -961,11 +1013,29 @@ local .l1
 	mov	[.i], ecx
 .grayscale_alpha2.extloop:
 	init_block
+	add	eax, eax
 	add	eax, edi
 	push	eax
-	mov	al, [esi]
-	add	esi, 2
-	block_byte_innerloop .grayscale_alpha2.extloop
+	lodsw
+macro block_word_innerloop extloop
+{
+local .l1
+.l1:
+	mov	ecx, ebx
+	rep	stosw
+	sub	edi, ebx
+	add	edi, [.row_distance]
+	dec	edx
+	jnz	.l1
+	pop	edi ebx
+	mov	eax, [.col_increment]
+	sub	[.i], eax
+	ja	extloop
+	add	edi, [.col_distance]
+	mov	eax, [.row_increment]
+	sub	[.j], eax
+}
+	block_word_innerloop .grayscale_alpha2.extloop
 	ja	.grayscale_alpha2.next
 	jmp	.convert_done
 .grayscale_alpha2_16bit:
@@ -979,12 +1049,17 @@ local .l1
 	mov	[.i], ecx
 .grayscale_alpha2_16bit.extloop:
 	init_block
+	add	eax, eax
 	add	eax, edi
 	push	eax
-	mov	ax, [esi]
-	add	esi, 4
+	lodsw
 	convert_16_to_8
-	block_byte_innerloop .grayscale_alpha2_16bit.extloop
+	mov	ecx, eax
+	lodsw
+	convert_16_to_8
+	mov	ah, cl
+	xchg	al, ah
+	block_word_innerloop .grayscale_alpha2_16bit.extloop
 	ja	.grayscale_alpha2_16bit
 .convert_done:
 ; next interlace pass
@@ -1070,7 +1145,7 @@ local .l1
 	jz	.graypal_common
 	mov	edx, 0xFFFFFF
 .graypal_common:
-	xor	eax, eax
+	mov	eax, 0xff000000
 @@:
 	stosd
 	add	eax, edx