Implement a small texture wrapper.

Allows for RAII use of OpenGL textures.

src/MultiImageVisualisation.cpp

@@ -49,18 +49,13 @@ MultiImageVisualisation::MultiImageVisualisation(const fmri::LayerData &layer)
     }
 }
 
-MultiImageVisualisation::~MultiImageVisualisation()
-{
-    glDeleteTextures(0, &texture);
-}
-
 void MultiImageVisualisation::render()
 {
     glEnableClientState(GL_TEXTURE_COORD_ARRAY);
     glEnableClientState(GL_VERTEX_ARRAY);
     glEnable(GL_TEXTURE_2D);
     glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
-    glBindTexture(GL_TEXTURE_2D, texture);
+    texture.bind(GL_TEXTURE_2D);
     glTexCoordPointer(2, GL_FLOAT, 0, texCoordBuffer.get());
     glVertexPointer(3, GL_FLOAT, 0, vertexBuffer.get());
     glDrawArrays(GL_QUADS, 0, nodePositions_.size() / 3 * 4);

src/MultiImageVisualisation.hpp

@@ -5,6 +5,7 @@
 #include <memory>
 #include "LayerVisualisation.hpp"
 #include "LayerData.hpp"
+#include "Texture.hpp"
 
 namespace fmri
 {
@@ -12,7 +13,6 @@ namespace fmri
     {
     public:
         explicit MultiImageVisualisation(const LayerData&);
-        ~MultiImageVisualisation() override;
 
         void render() override;
 
@@ -23,7 +23,7 @@ namespace fmri
                 0, 1, 1,
                 0, -1, 1,
         };
-        GLuint texture;
+        Texture texture;
         std::unique_ptr<float[]> vertexBuffer;
         std::unique_ptr<float[]> texCoordBuffer;
     };

src/Texture.cpp

@@ -0,0 +1,36 @@
+#include <algorithm>
+#include "Texture.hpp"
+
+using namespace fmri;
+
+Texture::Texture() noexcept
+{
+    glGenTextures(1, &id);
+}
+
+Texture::Texture(GLuint id) noexcept : id(id)
+{
+}
+
+Texture::~Texture()
+{
+    if (id != 0) {
+        glDeleteTextures(1, &id);
+    }
+}
+
+Texture &Texture::operator=(Texture && other) noexcept
+{
+    std::swap(id, other.id);
+    return *this;
+}
+
+Texture::Texture(Texture && other) noexcept
+{
+    std::swap(id, other.id);
+}
+
+void Texture::bind(GLenum target) const
+{
+    glBindTexture(target, id);
+}

src/Texture.hpp

@@ -0,0 +1,44 @@
+#pragma once
+
+#include <GL/gl.h>
+
+namespace fmri
+{
+    /**
+     * Simple owning Texture class.
+     *
+     * Encapsulates an OpenGL texture, and enables RAII for it. Copying
+     * is disallowed for this reason.
+     */
+    class Texture
+    {
+    public:
+        /**
+         * Allocate a new texture
+         */
+        Texture() noexcept;
+        Texture(Texture &&) noexcept;
+        Texture(const Texture &) = delete;
+
+        /**
+         * Own an existing texture
+         * @param id original texture ID.
+         */
+        explicit Texture(GLuint id) noexcept;
+
+        ~Texture();
+
+        Texture &operator=(Texture &&) noexcept;
+        Texture &operator=(const Texture &) = delete;
+
+        /**
+         * Bind the owned texture to the given spot.
+         * @param target valid target for glBindTexture.
+         */
+        void bind(GLenum target) const;
+
+    private:
+        GLuint id;
+
+    };
+}

src/glutils.cpp

@@ -8,6 +8,7 @@
 #include <thread>
 #include "glutils.hpp"
 #include "Range.hpp"
+#include "Texture.hpp"
 
 using namespace fmri;
 using namespace std;
@@ -32,17 +33,16 @@ static void rescaleSubImages(vector<float>& textureBuffer, int subImages) {
     }
 }
 
-GLuint fmri::loadTexture(DType const *data, int width, int height, int subImages)
+fmri::Texture fmri::loadTexture(DType const *data, int width, int height, int subImages)
 {
     // Load and scale texture
     vector<float> textureBuffer(data, data + (width * height));
     rescaleSubImages(textureBuffer, subImages);
 
     const float color[] = {1, 1, 1}; // Background color for textures.
-    GLuint texture;
-    glGenTextures(1, &texture);
 
-    glBindTexture(GL_TEXTURE_2D, texture);
+    Texture texture;
+    texture.bind(GL_TEXTURE_2D);
 
     // Set up (lack of) repetition
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_BORDER);

src/glutils.hpp

@@ -2,6 +2,7 @@
 
 #include "LayerData.hpp"
 #include "utils.hpp"
+#include "Texture.hpp"
 #include <GL/glut.h>
 #include <string_view>
 
@@ -15,7 +16,7 @@ namespace fmri {
      * @param subImages Number of subimages in the original image. Sub images are rescaled individually to preserve contrast. Optional, default 1.
      * @return A texture reference.
      */
-    GLuint loadTexture(DType const *data, int width, int height, int subImages = 1);
+    fmri::Texture loadTexture(DType const *data, int width, int height, int subImages = 1);
 
     /**
      * Callback handler to handle resizing windows.