From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 7 Oct 2013 11:08:19 +0000 (+0300)
Subject: Change the ImageLoader API to use IO::Seekable
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgui.git;a=commitdiff_plain;h=8e403dbbcde6efee1862f6d501ce30a3e7ba81c4

Change the ImageLoader API to use IO::Seekable

Trying to operate on purely streamed I/O turns out to be more headache
than it's worth.  I'll implement a generic adaptor in the IO namespace
if it's needed at a later point.
---

diff --git a/source/graphics/devil/devilloader.cpp b/source/graphics/devil/devilloader.cpp
index 23b04b3..392bde8 100644
--- a/source/graphics/devil/devilloader.cpp
+++ b/source/graphics/devil/devilloader.cpp
@@ -6,90 +6,51 @@ using namespace std;
 
 namespace {
 
-struct IOContext
-{
-	Msp::IO::Base *io;
-	char *buffer;
-	unsigned buf_fill;
-	unsigned buf_max;
-	unsigned position;
-};
-
 unsigned char eof(void *handle)
 {
-	return reinterpret_cast<IOContext *>(handle)->io->eof();
+	return reinterpret_cast<Msp::IO::Seekable *>(handle)->eof();
 }
 
 int get(void *handle)
 {
-	IOContext *ctx = reinterpret_cast<IOContext *>(handle);
-	if(ctx->position<ctx->buf_fill)
-		return ctx->buffer[ctx->position++];
-	else
-	{
-		char c = ctx->io->get();
-		if(ctx->position<ctx->buf_max)
-			ctx->buffer[ctx->position] = c;
-		++ctx->position;
-		return c;
-	}
+	return reinterpret_cast<Msp::IO::Seekable *>(handle)->get();
 }
 
 int read(void *buf, unsigned size, unsigned count, void *handle)
 {
-	IOContext *ctx = reinterpret_cast<IOContext *>(handle);
+	Msp::IO::Seekable *io = reinterpret_cast<Msp::IO::Seekable *>(handle);
 	char *cbuf = reinterpret_cast<char *>(buf);
-	unsigned len = size*count;
-	unsigned ret = 0;
-
-	if(ctx->position<ctx->buf_fill)
+	unsigned i = 0;
+	for(; i<count; ++i)
 	{
-		unsigned copy_len = min(ctx->buf_fill-ctx->position, len);
-		copy(ctx->buffer+ctx->position, ctx->buffer+ctx->position+copy_len, cbuf);
-		ctx->position += copy_len;
-		ret += copy_len;
-		cbuf += copy_len;
-		len -= copy_len;
+		unsigned len = io->read(cbuf, size);
+		cbuf += size;
+		if(len<size)
+			break;
 	}
-
-	if(len)
-	{
-		unsigned read_len = ctx->io->read(cbuf, len);
-		if(ctx->position<ctx->buf_max)
-		{
-			unsigned copy_len = min(ctx->buf_max-ctx->position, read_len);
-			copy(cbuf, cbuf+copy_len, ctx->buffer+ctx->position);
-			ctx->buf_fill += copy_len;
-		}
-		ret += read_len;
-		ctx->position += read_len;
-	}
-
-	return ret;
+	return i;
 }
 
-int seek(void *handle, int offset, int type)
+int seek(void *handle, int offset, int il_type)
 {
-	IOContext *ctx = reinterpret_cast<IOContext *>(handle);
-
-	unsigned new_pos = ctx->position;
-	if(type==IL_SEEK_SET)
-		new_pos = offset;
-	else if(type==IL_SEEK_CUR)
-		new_pos += offset;
+	Msp::IO::SeekType type;
+	if(il_type==IL_SEEK_SET)
+		type = Msp::IO::S_BEG;
+	else if(il_type==IL_SEEK_CUR)
+		type = Msp::IO::S_CUR;
+	else if(il_type==IL_SEEK_END)
+		type = Msp::IO::S_END;
 	else
 		return -1;
 
-	if(new_pos>ctx->buf_fill)
-		new_pos = ctx->buf_fill;
-	ctx->position = new_pos;
+	reinterpret_cast<Msp::IO::Seekable *>(handle)->seek(offset, type);
 
 	return 0;
 }
 
 int tell(void *handle)
 {
-	return reinterpret_cast<IOContext *>(handle)->position;
+	return reinterpret_cast<Msp::IO::Seekable *>(handle)->tell();
 }
 
 } // namespace
@@ -98,9 +59,8 @@ int tell(void *handle)
 namespace Msp {
 namespace Graphics {
 
-DevilLoader::DevilLoader(IO::Base &i, const string &s):
-	io(i),
-	signature(s)
+DevilLoader::DevilLoader(IO::Seekable &i):
+	io(i)
 {
 	static bool il_init_done = false;
 
@@ -128,18 +88,9 @@ bool DevilLoader::detect(const string &sig)
 
 void DevilLoader::load(Image::Data &data)
 {
-	IOContext ctx;
-	ctx.io = &io;
-	char buffer[4096];
-	ctx.buffer = buffer;
-	ctx.buf_max = sizeof(buffer);
-	copy(signature.begin(), signature.end(), buffer);
-	ctx.buf_fill = signature.size();
-	ctx.position = 0;
-
 	ilSetRead(0, 0, eof, get, read, seek, tell);
 	ilBindImage(id);
-	ilLoadF(IL_TYPE_UNKNOWN, &ctx);
+	ilLoadF(IL_TYPE_UNKNOWN, &io);
 
 	switch(ilGetInteger(IL_IMAGE_FORMAT))
 	{
diff --git a/source/graphics/devil/devilloader.h b/source/graphics/devil/devilloader.h
index 3791bb2..3b933ae 100644
--- a/source/graphics/devil/devilloader.h
+++ b/source/graphics/devil/devilloader.h
@@ -10,11 +10,10 @@ class DevilLoader: public ImageLoader
 {
 private:
 	IO::Base &io;
-	std::string signature;
 	unsigned id;
 
 public:
-	DevilLoader(IO::Base &, const std::string &);
+	DevilLoader(IO::Seekable &);
 	virtual ~DevilLoader();
 
 	static bool detect(const std::string &);
diff --git a/source/graphics/image.cpp b/source/graphics/image.cpp
index 3e1124f..b22be19 100644
--- a/source/graphics/image.cpp
+++ b/source/graphics/image.cpp
@@ -29,7 +29,7 @@ void Image::load_file(const string &fn)
 	load(*loader);
 }
 
-void Image::load_io(IO::Base &io)
+void Image::load_io(IO::Seekable &io)
 {
 	RefPtr<ImageLoader> loader = ImageLoader::open_io(io);
 	load(*loader);
diff --git a/source/graphics/image.h b/source/graphics/image.h
index bfaeef8..6905461 100644
--- a/source/graphics/image.h
+++ b/source/graphics/image.h
@@ -3,7 +3,7 @@
 
 #include <stdexcept>
 #include <string>
-#include <msp/io/base.h>
+#include <msp/io/seekable.h>
 #include "pixelformat.h"
 
 namespace Msp {
@@ -30,7 +30,7 @@ private:
 
 public:
 	void load_file(const std::string &);
-	void load_io(IO::Base &);
+	void load_io(IO::Seekable &);
 	void load(ImageLoader &);
 
 	PixelFormat get_format() const { return data.fmt; }
diff --git a/source/graphics/imageloader.cpp b/source/graphics/imageloader.cpp
index 679f797..daedab6 100644
--- a/source/graphics/imageloader.cpp
+++ b/source/graphics/imageloader.cpp
@@ -38,11 +38,12 @@ ImageLoader *ImageLoader::open_file(const string &fn)
 	}
 }
 
-ImageLoader *ImageLoader::open_io(IO::Base &io)
+ImageLoader *ImageLoader::open_io(IO::Seekable &io)
 {
 	char sig_buf[8];
 	unsigned sig_len = io.read(sig_buf, sizeof(sig_buf));
 	string sig(sig_buf, sig_len);
+	io.seek(0, IO::S_BEG);
 
 	// TODO register loader classes automatically
 	ImageLoader *loader = 0;
@@ -50,11 +51,11 @@ ImageLoader *ImageLoader::open_io(IO::Base &io)
 		;
 #ifdef WITH_LIBPNG
 	else if(PngLoader::detect(sig))
-		loader = new PngLoader(io, sig);
+		loader = new PngLoader(io);
 #endif
 #ifdef WITH_DEVIL
 	else if(DevilLoader::detect(sig))
-		loader = new DevilLoader(io, sig);
+		loader = new DevilLoader(io);
 #endif
 	else
 	{
diff --git a/source/graphics/imageloader.h b/source/graphics/imageloader.h
index 0653275..f953990 100644
--- a/source/graphics/imageloader.h
+++ b/source/graphics/imageloader.h
@@ -32,7 +32,7 @@ public:
 	virtual ~ImageLoader();
 
 	static ImageLoader *open_file(const std::string &);
-	static ImageLoader *open_io(IO::Base &);
+	static ImageLoader *open_io(IO::Seekable &);
 
 	virtual void load(Image::Data &) = 0;
 };
diff --git a/source/graphics/png/pngloader.cpp b/source/graphics/png/pngloader.cpp
index 8553065..3f2f959 100644
--- a/source/graphics/png/pngloader.cpp
+++ b/source/graphics/png/pngloader.cpp
@@ -31,7 +31,7 @@ struct PngLoader::Private
 	png_info *info;
 };
 
-PngLoader::PngLoader(IO::Base &io, const string &sig):
+PngLoader::PngLoader(IO::Base &io, unsigned sig_bytes):
 	priv(new Private)
 {
 	priv->png = png_create_read_struct(PNG_LIBPNG_VER_STRING, &priv->message, error, 0);
@@ -39,7 +39,7 @@ PngLoader::PngLoader(IO::Base &io, const string &sig):
 
 	// These probably won't give any errors
 	png_set_read_fn(priv->png, &io, read);
-	png_set_sig_bytes(priv->png, sig.size());
+	png_set_sig_bytes(priv->png, sig_bytes);
 }
 
 PngLoader::~PngLoader()
diff --git a/source/graphics/png/pngloader.h b/source/graphics/png/pngloader.h
index 0bb5fd7..a81c34c 100644
--- a/source/graphics/png/pngloader.h
+++ b/source/graphics/png/pngloader.h
@@ -14,7 +14,7 @@ private:
 	Private *priv;
 
 public:
-	PngLoader(IO::Base &, const std::string &);
+	PngLoader(IO::Base &, unsigned = 0);
 	virtual ~PngLoader();
 
 	static bool detect(const std::string &);