Separate out the actual screenshot comparison.

Fixes #109.

CMakeLists.txt

@@ -918,7 +918,11 @@ if(WIN32)
 endif()
 
 if(HEADLESS)
-	add_executable(PPSSPPHeadless headless/Headless.cpp headless/StubHost.h)
+	add_executable(PPSSPPHeadless
+		headless/Headless.cpp
+		headless/StubHost.h
+		headless/Compare.cpp
+		headless/Compare.h)
 	target_link_libraries(PPSSPPHeadless ${CoreLibName}
 		${COCOA_LIBRARY} ${CMAKE_THREAD_LIBS_INIT})
 	setup_target_project(PPSSPPHeadless headless)

headless/Compare.cpp

@@ -0,0 +1,77 @@
+// Copyright (c) 2012- PPSSPP Project.
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, version 2.0 or later versions.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License 2.0 for more details.
+
+// A copy of the GPL 2.0 should have been included with the program.
+// If not, see http://www.gnu.org/licenses/
+
+// Official git repository and contact information can be found at
+// https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.
+
+#include "Compare.h"
+#include "FileUtil.h"
+
+#include <math.h>
+
+bool CompareOutput(const std::string bootFilename)
+{
+	std::string expect_filename = bootFilename.substr(bootFilename.length() - 4) + ".expected";
+	if (File::Exists(expect_filename))
+	{
+		// TODO: Do the compare here
+		return true;
+	}
+	else
+	{
+		fprintf(stderr, "Expectation file %s not found", expect_filename.c_str());
+		return false;
+	}
+}
+
+inline int ComparePixel(u32 pix1, u32 pix2)
+{
+	// For now, if they're different at all except alpha, it's an error.
+	if ((pix1 & 0xFFFFFF) != (pix2 & 0xFFFFFF))
+		return 1;
+	return 0;
+}
+
+double CompareScreenshot(const u8 *pixels, int w, int h, int stride, const std::string screenshotFilename, std::string &error)
+{
+	u32 *pixels32 = (u32 *) pixels;
+	// We assume the bitmap is the specified size, not including whatever stride.
+	u32 *reference = (u32 *) calloc(w * h, sizeof(u32));
+
+	FILE *bmp = fopen(screenshotFilename.c_str(), "rb");
+	if (bmp)
+	{
+		// The bitmap header is 14 + 40 bytes.  We could validate it but the test would fail either way.
+		fseek(bmp, 14 + 40, SEEK_SET);
+		fread(reference, sizeof(u32), w * h, bmp);
+		fclose(bmp);
+	}
+	else
+	{
+		error = "Unable to read screenshot: " + screenshotFilename;
+		free(reference);
+		return -1.0f;
+	}
+
+	u32 errors = 0;
+	for (int y = 0; y < h; ++y)
+	{
+		for (int x = 0; x < w; ++x)
+			errors += ComparePixel(pixels32[y * stride + x], reference[y * w + x]);
+	}
+
+	free(reference);
+
+	return (double) errors / (double) (w * h);
+}

headless/Compare.h

@@ -0,0 +1,23 @@
+// Copyright (c) 2012- PPSSPP Project.
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, version 2.0 or later versions.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License 2.0 for more details.
+
+// A copy of the GPL 2.0 should have been included with the program.
+// If not, see http://www.gnu.org/licenses/
+
+// Official git repository and contact information can be found at
+// https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.
+
+#include <string>
+
+#include "Globals.h"
+
+bool CompareOutput(std::string bootFilename);
+double CompareScreenshot(const u8 *pixels, int w, int h, int stride, const std::string screenshotFilename, std::string &error);

headless/Headless.cpp

@@ -13,6 +13,7 @@
 #include "Log.h"
 #include "LogManager.h"
 
+#include "Compare.h"
 #include "StubHost.h"
 #ifdef _WIN32
 #include "WindowsHeadlessHost.h"
@@ -204,17 +205,7 @@ int main(int argc, const char* argv[])
 	headlessHost = NULL;
 
 	if (autoCompare)
-	{
-		std::string expect_filename = std::string(bootFilename).substr(strlen(bootFilename - 4)) + ".expected";
-		if (File::Exists(expect_filename))
-		{
-			// TODO: Do the compare here
-		}
-		else
-		{
-			fprintf(stderr, "Expectation file %s not found", expect_filename.c_str());
-		}
-	}
+		CompareOutput(bootFilename);
 
 	return 0;
 }

headless/Headless.vcxproj

@@ -145,6 +145,7 @@
   </ItemDefinitionGroup>
   <ItemGroup>
     <ClCompile Include="..\native\ext\glew\glew.c" />
+    <ClCompile Include="Compare.cpp" />
     <ClCompile Include="Headless.cpp">
       <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">NotUsing</PrecompiledHeader>
       <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">NotUsing</PrecompiledHeader>
@@ -177,6 +178,7 @@
     </ProjectReference>
   </ItemGroup>
   <ItemGroup>
+    <ClInclude Include="Compare.h" />
     <ClInclude Include="StubHost.h" />
     <ClInclude Include="WindowsHeadlessHost.h" />
   </ItemGroup>

headless/Headless.vcxproj.filters

@@ -4,6 +4,7 @@
     <ClCompile Include="Headless.cpp" />
     <ClCompile Include="..\native\ext\glew\glew.c" />
     <ClCompile Include="WindowsHeadlessHost.cpp" />
+    <ClCompile Include="Compare.cpp" />
   </ItemGroup>
   <ItemGroup>
     <None Include="headless.txt" />
@@ -11,5 +12,6 @@
   <ItemGroup>
     <ClInclude Include="StubHost.h" />
     <ClInclude Include="WindowsHeadlessHost.h" />
+    <ClInclude Include="Compare.h" />
   </ItemGroup>
 </Project>

headless/WindowsHeadlessHost.cpp

@@ -16,6 +16,7 @@
 // https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.
 
 #include "WindowsHeadlessHost.h"
+#include "Compare.h"
 
 #include <stdio.h>
 #include <windows.h>
@@ -94,44 +95,34 @@ void WindowsHeadlessHost::SendDebugScreenshot(const u8 *pixbuf, u32 w, u32 h)
 	// We ignore the current framebuffer parameters and just grab the full screen.
 	const static int FRAME_WIDTH = 512;
 	const static int FRAME_HEIGHT = 272;
-	u32 *pixels = (u32 *) calloc(FRAME_WIDTH * FRAME_HEIGHT, sizeof(u32));
-	u32 *reference = (u32 *) calloc(FRAME_WIDTH * FRAME_HEIGHT, sizeof(u32));
+	u8 *pixels = new u8[FRAME_WIDTH * FRAME_HEIGHT * 4];
 
 	// TODO: Maybe the GPU should do this?
 	glReadBuffer(GL_FRONT);
 	glReadPixels(0, 0, FRAME_WIDTH, FRAME_HEIGHT, GL_BGRA, GL_UNSIGNED_BYTE, pixels);
 
-	BITMAPFILEHEADER header;
-	BITMAPINFOHEADER infoHeader;
-	FILE *bmp = fopen(comparisonScreenshot.c_str(), "rb");
-	if (bmp)
-	{
-		fread(&header, sizeof(header), 1, bmp);
-		fread(&infoHeader, sizeof(infoHeader), 1, bmp);
-		fread(reference, sizeof(u32), FRAME_WIDTH * FRAME_HEIGHT, bmp);
-		fclose(bmp);
-	}
-	else
-		fprintf_s(out, "Unable to read screenshot: %s\n", comparisonScreenshot.c_str());
+	std::string error;
+	double errors = CompareScreenshot(pixels, FRAME_WIDTH, FRAME_HEIGHT, FRAME_WIDTH, comparisonScreenshot, error);
+	if (errors < 0)
+		fprintf_s(out, "%s\n", error.c_str());
 
-	// TODO: Better error rate and move to headless/shared between platforms.
-	int errors = 0;
-	for (int i = 0; i < FRAME_WIDTH * FRAME_HEIGHT; ++i)
+	if (errors > 0)
 	{
-		// Ignore alpha.
-		// TODO: Error threshold?
-		errors += (pixels[i] & 0xFFFFFF) != (reference[i] & 0xFFFFFF) ? 1 : 0;
-	}
+		fprintf_s(out, "Screenshot error: %f%%\n", errors * 100.0f);
 
-	if (errors != 0)
-	{
-		fprintf_s(out, "Screenshot error: %f%%\n", (float) errors * 100.0f / (float) (FRAME_WIDTH * FRAME_HEIGHT));
+		// Lazy, just read in the original header to output the failed screenshot.
+		u8 header[14 + 40] = {0};
+		FILE *bmp = fopen(comparisonScreenshot.c_str(), "rb");
+		if (bmp)
+		{
+			fread(&header, sizeof(header), 1, bmp);
+			fclose(bmp);
+		}
 
 		FILE *saved = fopen("__testfailure.bmp", "wb");
 		if (saved)
 		{
 			fwrite(&header, sizeof(header), 1, saved);
-			fwrite(&infoHeader, sizeof(infoHeader), 1, saved);
 			fwrite(pixels, sizeof(u32), FRAME_WIDTH * FRAME_HEIGHT, saved);
 			fclose(saved);
 
@@ -139,8 +130,7 @@ void WindowsHeadlessHost::SendDebugScreenshot(const u8 *pixbuf, u32 w, u32 h)
 		}
 	}
 
-	free(pixels);
-	free(reference);
+	delete [] pixels;
 }
 
 void WindowsHeadlessHost::SetComparisonScreenshot(const std::string &filename)