cur support untested

ico.d

@@ -1,9 +1,11 @@
 /++
-	Load (and, in the future, save) support for Windows .ico icon files.
+	Load and save support for Windows .ico icon files. It also supports .cur files, but I've not actually tested them yet.
 
 	History:
 		Written July 21, 2022 (dub v10.9)
 
+		Save support added April 21, 2023 (dub v11.0)
+
 	Examples:
 
 	---
@@ -36,12 +38,30 @@ module arsd.ico;
 import arsd.png;
 import arsd.bmp;
 
+/++
+	A representation of a cursor image as found in a .cur file.
+
+	History:
+		Added April 21, 2023 (dub v11.0)
++/
+struct IcoCursor {
+	MemoryImage image;
+	int hotspotX;
+	int hotspotY;
+}
+
+/++
+	The header of a .ico or .cur file. Note the alignment is $(I not) correct for slurping the file.
++/
 struct IcoHeader {
 	ushort reserved;
 	ushort imageType; // 1 = icon, 2 = cursor
 	ushort numberOfImages;
 }
 
+/++
+	The icon directory entry of a .ico or .cur file. Note the alignment is $(I not) correct for slurping the file.
++/
 struct ICONDIRENTRY {
 	ubyte width; // 0 == 256
 	ubyte height; // 0 == 256
@@ -75,6 +95,62 @@ MemoryImage[] loadIco(string filename) {
 
 /// ditto
 MemoryImage[] loadIcoFromMemory(const(ubyte)[] data) {
+	MemoryImage[] images;
+	int spot;
+	loadIcoOrCurFromMemoryCallback(
+		data,
+		(int imageType, int numberOfImages) {
+			if(imageType > 1)
+				throw new Exception("Not an icon file - invalid image type header");
+
+			images.length = numberOfImages;
+		},
+		(MemoryImage mi, int hotspotX, int hotspotY) {
+			images[spot++] = mi;
+		}
+	);
+
+	assert(spot == images.length);
+
+	return images;
+}
+
+/++
+	Loads a .cur file.
+
+	History:
+		Added April 21, 2023 (dub v11.0)
++/
+IcoCursor[] loadCurFromMemory(const(ubyte)[] data) {
+	IcoCursor[] images;
+	int spot;
+	loadIcoOrCurFromMemoryCallback(
+		data,
+		(int imageType, int numberOfImages) {
+			if(imageType != 2)
+				throw new Exception("Not an cursor file - invalid image type header");
+
+			images.length = numberOfImages;
+		},
+		(MemoryImage mi, int hotspotX, int hotspotY) {
+			images[spot++] = IcoCursor(mi, hotspotX, hotspotY);
+		}
+	);
+
+	assert(spot == images.length);
+
+	return images;
+
+}
+
+/++
+	Load implementation. Api subject to change.
++/
+void loadIcoOrCurFromMemoryCallback(
+	const(ubyte)[] data,
+	scope void delegate(int imageType, int numberOfImages) imageTypeChecker,
+	scope void delegate(MemoryImage mi, int hotspotX, int hotspotY) encounteredImage,
+) {
 	IcoHeader header;
 	if(data.length < 6)
 		throw new Exception("Not an icon file - too short to have a header");
@@ -89,8 +165,8 @@ MemoryImage[] loadIcoFromMemory(const(ubyte)[] data) {
 
 	if(header.reserved != 0)
 		throw new Exception("Not an icon file - first bytes incorrect");
-	if(header.imageType > 1)
+
-		throw new Exception("Not an icon file - invalid image type header");
+	imageTypeChecker(header.imageType, header.numberOfImages);
 
 	auto originalData = data;
 	data = data[6 .. $];
@@ -133,7 +209,6 @@ MemoryImage[] loadIcoFromMemory(const(ubyte)[] data) {
 	foreach(i; 0 .. header.numberOfImages)
 		ides ~= readDirEntry();
 
-	MemoryImage[] images;
 	foreach(image; ides) {
 		if(image.imageDataOffset >= originalData.length)
 			throw new Exception("Invalid icon file - image data offset beyond file size");
@@ -146,12 +221,104 @@ MemoryImage[] loadIcoFromMemory(const(ubyte)[] data) {
 			throw new Exception("Invalid image, not long enough to identify");
 
 		if(idata[0 .. 4] == "\x89PNG") {
-			images ~= readPngFromBytes(idata);
+			encounteredImage(readPngFromBytes(idata), image.planesOrHotspotX, image.bppOrHotspotY);
 		} else {
-			images ~= readBmp(idata, false, false, true);
+			encounteredImage(readBmp(idata, false, false, true), image.planesOrHotspotX, image.bppOrHotspotY);
+		}
 	}
 }
 
-	return images;
+/++
+	History:
+		Added April 21, 2023 (dub v11.0)
++/
+void writeIco(string filename, MemoryImage[] images) {
+	writeIcoOrCur(filename, false, cast(int) images.length, (int idx) { return IcoCursor(images[idx]); });
 }
 
+/// ditto
+void writeCur(string filename, IcoCursor[] images) {
+	writeIcoOrCur(filename, true, cast(int) images.length, (int idx) { return images[idx]; });
+}
+
+/++
+	Save implementation. Api subject to change.
++/
+void writeIcoOrCur(string filename, bool isCursor, int count, scope IcoCursor delegate(int) getImageAndHotspots) {
+	IcoHeader header;
+	header.reserved = 0;
+	header.imageType = isCursor ? 2 : 1;
+	if(count > ushort.max)
+		throw new Exception("too many images for icon file");
+	header.numberOfImages = cast(ushort) count;
+
+	enum headerSize = 6;
+	enum dirEntrySize = 16;
+
+	int dataFilePos = headerSize + dirEntrySize * cast(int) count;
+
+	ubyte[][] pngs;
+	ICONDIRENTRY[] dirEntries;
+	dirEntries.length = count;
+	pngs.length = count;
+	foreach(idx, ref entry; dirEntries) {
+		auto image = getImageAndHotspots(cast(int) idx);
+		if(image.image.width > 256 || image.image.height > 256)
+			throw new Exception("image too big for icon file");
+		entry.width = image.image.width == 256 ? 0 : cast(ubyte) image.image.width;
+		entry.height = image.image.height == 256 ? 0 : cast(ubyte) image.image.height;
+
+		entry.planesOrHotspotX = isCursor ? cast(ushort) image.hotspotX : 0;
+		entry.bppOrHotspotY = isCursor ? cast(ushort) image.hotspotY : 0;
+
+		auto png = writePngToArray(image.image);
+
+		entry.imageDataSize = cast(uint) png.length;
+		entry.imageDataOffset = dataFilePos;
+		dataFilePos += entry.imageDataSize;
+
+		pngs[idx] = png;
+	}
+
+	ubyte[] data;
+	data.length = dataFilePos;
+	int pos = 0;
+
+	data[pos++] = (header.reserved >> 0) & 0xff;
+	data[pos++] = (header.reserved >> 8) & 0xff;
+	data[pos++] = (header.imageType >> 0) & 0xff;
+	data[pos++] = (header.imageType >> 8) & 0xff;
+	data[pos++] = (header.numberOfImages >> 0) & 0xff;
+	data[pos++] = (header.numberOfImages >> 8) & 0xff;
+
+	foreach(entry; dirEntries) {
+		data[pos++] = (entry.width >> 0) & 0xff;
+		data[pos++] = (entry.height >> 0) & 0xff;
+		data[pos++] = (entry.numColors >> 0) & 0xff;
+		data[pos++] = (entry.reserved >> 0) & 0xff;
+		data[pos++] = (entry.planesOrHotspotX >> 0) & 0xff;
+		data[pos++] = (entry.planesOrHotspotX >> 8) & 0xff;
+		data[pos++] = (entry.bppOrHotspotY >> 0) & 0xff;
+		data[pos++] = (entry.bppOrHotspotY >> 8) & 0xff;
+
+		data[pos++] = (entry.imageDataSize >> 0) & 0xff;
+		data[pos++] = (entry.imageDataSize >> 8) & 0xff;
+		data[pos++] = (entry.imageDataSize >> 16) & 0xff;
+		data[pos++] = (entry.imageDataSize >> 24) & 0xff;
+
+		data[pos++] = (entry.imageDataOffset >> 0) & 0xff;
+		data[pos++] = (entry.imageDataOffset >> 8) & 0xff;
+		data[pos++] = (entry.imageDataOffset >> 16) & 0xff;
+		data[pos++] = (entry.imageDataOffset >> 24) & 0xff;
+	}
+
+	foreach(png; pngs) {
+		data[pos .. pos + png.length] = png[];
+		pos += png.length;
+	}
+
+	assert(pos == dataFilePos);
+
+	import std.file;
+	std.file.write(filename, data);
+}