From 1d2485fd282c6cda8605fcc65ef2098f447cd203 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Thu, 20 Aug 2015 00:25:44 +0200
Subject: [PATCH] Pixel storage support, part 7: state tracking for
 glPixelStore().

---
 src/Magnum/Context.cpp                      |  6 +++
 src/Magnum/Context.h                        | 11 +++--
 src/Magnum/Implementation/RendererState.cpp | 52 +++++++++++++++++++++
 src/Magnum/Implementation/RendererState.h   | 32 +++++++++++++
 4 files changed, 97 insertions(+), 4 deletions(-)

diff --git a/src/Magnum/Context.cpp b/src/Magnum/Context.cpp
index 25191efc3..80194a847 100644
--- a/src/Magnum/Context.cpp
+++ b/src/Magnum/Context.cpp
@@ -48,6 +48,7 @@
 #include "Implementation/BufferState.h"
 #include "Implementation/FramebufferState.h"
 #include "Implementation/MeshState.h"
+#include "Implementation/RendererState.h"
 #include "Implementation/ShaderProgramState.h"
 #include "Implementation/TextureState.h"
 #ifndef MAGNUM_TARGET_GLES2
@@ -678,6 +679,11 @@ void Context::resetState(const States states) {
     if(states & State::Meshes)
         _state->mesh->reset();
 
+    if(states & State::PixelStorage) {
+        _state->renderer->unpackPixelStorage.reset();
+        _state->renderer->packPixelStorage.reset();
+    }
+
     /* Nothing to reset for renderer yet */
 
     if(states & State::Shaders) {
diff --git a/src/Magnum/Context.h b/src/Magnum/Context.h
index 7b4e1ad2f..1ac5214a6 100644
--- a/src/Magnum/Context.h
+++ b/src/Magnum/Context.h
@@ -154,18 +154,21 @@ class MAGNUM_EXPORT Context {
             /** Reset tracked mesh-related bindings */
             Meshes = 1 << 2,
 
+            /** Reset tracked pixel storage-related state */
+            PixelStorage = 1 << 3,
+
             /** Reset tracked renderer-related state */
-            Renderer = 1 << 3,
+            Renderer = 1 << 4,
 
             /** Reset tracked shader-related bindings */
-            Shaders = 1 << 4,
+            Shaders = 1 << 5,
 
             /** Reset tracked texture-related bindings and state */
-            Textures = 1 << 5,
+            Textures = 1 << 6,
 
             #ifndef MAGNUM_TARGET_GLES2
             /** Reset tracked transform feedback-related bindings */
-            TransformFeedback = 1 << 6
+            TransformFeedback = 1 << 7
             #endif
         };
 
diff --git a/src/Magnum/Implementation/RendererState.cpp b/src/Magnum/Implementation/RendererState.cpp
index efbdcf42b..d878f7fe7 100644
--- a/src/Magnum/Implementation/RendererState.cpp
+++ b/src/Magnum/Implementation/RendererState.cpp
@@ -70,6 +70,58 @@ RendererState::RendererState(Context& context, std::vector<std::string>& extensi
     static_cast<void>(context);
     static_cast<void>(extensions);
     #endif
+
+    /* In case the extensions are not supported on ES2, row length is
+       constantly 0 to avoid modifying that state */
+    #if !(defined(MAGNUM_TARGET_GLES2) && defined(MAGNUM_TARGET_WEBGL))
+    unpackPixelStorage.disengagedRowLength = PixelStorage::DisengagedValue;
+    packPixelStorage.disengagedRowLength = PixelStorage::DisengagedValue;
+    #ifdef MAGNUM_TARGET_GLES2
+    if(!context.isExtensionSupported<Extensions::GL::EXT::unpack_subimage>())
+        unpackPixelStorage.disengagedRowLength = 0;
+    if(!context.isExtensionSupported<Extensions::GL::NV::pack_subimage>())
+        packPixelStorage.disengagedRowLength = 0;
+    #endif
+    #endif
+}
+
+RendererState::PixelStorage::PixelStorage():
+    #ifndef MAGNUM_TARGET_GLES
+    swapBytes{false},
+    #endif
+    alignment{4}
+    #if !(defined(MAGNUM_TARGET_GLES2) && defined(MAGNUM_TARGET_WEBGL))
+    , rowLength{0}
+    #endif
+    #ifndef MAGNUM_TARGET_GLES2
+    , imageHeight{0},
+    skip{0}
+    #endif
+    #ifndef MAGNUM_TARGET_GLES
+    , compressedBlockSize{0},
+    compressedBlockDataSize{0}
+    #endif
+    {}
+
+void RendererState::PixelStorage::reset() {
+    #ifndef MAGNUM_TARGET_GLES
+    swapBytes = std::nullopt;
+    #endif
+    alignment = DisengagedValue;
+    #if !(defined(MAGNUM_TARGET_GLES2) && defined(MAGNUM_TARGET_WEBGL))
+    /* Resets to 0 instead of DisengagedValue in case the EXT_unpack_subimage/
+       NV_pack_image ES2 extension is not supported to avoid modifying that
+       state */
+    rowLength = disengagedRowLength;
+    #endif
+    #ifndef MAGNUM_TARGET_GLES2
+    imageHeight = DisengagedValue;
+    skip = Vector3i{DisengagedValue};
+    #endif
+    #ifndef MAGNUM_TARGET_GLES
+    compressedBlockSize = Vector3i{DisengagedValue};
+    compressedBlockDataSize = DisengagedValue;
+    #endif
 }
 
 }}
diff --git a/src/Magnum/Implementation/RendererState.h b/src/Magnum/Implementation/RendererState.h
index 581a843de..8abb59351 100644
--- a/src/Magnum/Implementation/RendererState.h
+++ b/src/Magnum/Implementation/RendererState.h
@@ -29,6 +29,8 @@
 #include <vector>
 
 #include "Magnum/Renderer.h"
+#include "Magnum/Math/Vector3.h"
+#include "MagnumExternal/Optional/optional.hpp"
 
 namespace Magnum { namespace Implementation {
 
@@ -41,6 +43,36 @@ struct RendererState {
 
     Renderer::ResetNotificationStrategy resetNotificationStrategy;
     #endif
+
+    struct PixelStorage {
+        enum: Int { DisengagedValue = -1 };
+
+        explicit PixelStorage();
+
+        void reset();
+
+        #ifndef MAGNUM_TARGET_GLES
+        std::optional<bool> swapBytes;
+        #endif
+        Int alignment;
+        #if !(defined(MAGNUM_TARGET_GLES2) && defined(MAGNUM_TARGET_WEBGL))
+        Int rowLength;
+        #endif
+        #ifndef MAGNUM_TARGET_GLES2
+        Int imageHeight;
+        Vector3i skip;
+        #endif
+        #ifndef MAGNUM_TARGET_GLES
+        Vector3i compressedBlockSize;
+        Int compressedBlockDataSize;
+        #endif
+
+        #if !(defined(MAGNUM_TARGET_GLES2) && defined(MAGNUM_TARGET_WEBGL))
+        Int disengagedRowLength;
+        #endif
+    };
+
+    PixelStorage packPixelStorage, unpackPixelStorage;
 };
 
 }}