cairo: fixed cairo for opengl 3.3

rxdu · Nov 14, 2024 · a36bcf9 · a36bcf9
1 parent 3a1feb4
commit a36bcf9
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Showing 3 changed files with 28 additions and 6 deletions.
diff --git a/src/imview/include/imview/component/cairo_context.hpp b/src/imview/include/imview/component/cairo_context.hpp
@@ -11,7 +11,6 @@
 #define CAIRO_CONTEXT_HPP
 
 #include <cairo.h>
-#include <GL/gl.h>
 
 #include <cstdint>
 #include <stack>
@@ -51,7 +50,7 @@ class CairoContext {
   void PopScale();
 
   // GL-related functions can only be called after a GL context has been created
-  GLuint RenderToGlTexture();
+  uint32_t RenderToGlTexture();
 
   // get object of Cairo context and surface
   cairo_t* GetCairoObject() { return cr_; }
@@ -67,7 +66,7 @@ class CairoContext {
 
   cairo_surface_t* surface_ = nullptr;
   cairo_t* cr_ = nullptr;
-  GLuint image_texture_;
+  uint32_t image_texture_;
 
   float aspect_ratio_ = 1.0;
 

diff --git a/src/imview/src/component/cairo_context.cpp b/src/imview/src/component/cairo_context.cpp
@@ -9,6 +9,8 @@
 
 #include "imview/component/cairo_context.hpp"
 
+#include <glad/glad.h>
+
 #include <iostream>
 
 namespace quickviz {
@@ -89,13 +91,34 @@ void CairoContext::PopScale() {
   scaler_stack_.pop();
 }
 
-GLuint CairoContext::RenderToGlTexture() {
+uint32_t CairoContext::RenderToGlTexture() {
   // bind texture
   glBindTexture(GL_TEXTURE_2D, image_texture_);
 
   // convert surface to OpenGL texture
   unsigned char* data = cairo_image_surface_get_data(surface_);
-  glTexImage2D(GL_TEXTURE_2D, 0, 4, width_, height_, 0, GL_BGRA,
+  cairo_format_t format = cairo_image_surface_get_format(surface_);
+  GLenum gl_format;
+  if (format == CAIRO_FORMAT_ARGB32) {
+    gl_format = GL_RGBA;
+    for (int i = 0; i < width_ * height_; ++i) {
+      unsigned char* pixel = &data[i * 4];
+      unsigned char a = pixel[3];
+      unsigned char r = pixel[2];
+      unsigned char g = pixel[1];
+      unsigned char b = pixel[0];
+      pixel[0] = r;
+      pixel[1] = g;
+      pixel[2] = b;
+      pixel[3] = a;
+    }
+  } else if (format == CAIRO_FORMAT_RGB24) {
+    gl_format = GL_RGB;
+  } else {
+    throw std::runtime_error(
+        "[ERROR] render_to_gl_texture() - Unsupported Cairo format\n");
+  }
+  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width_, height_, 0, gl_format,
                GL_UNSIGNED_BYTE, data);
 
   // unbind texture

diff --git a/src/imview/src/widget/cairo_widget.cpp b/src/imview/src/widget/cairo_widget.cpp
@@ -92,7 +92,7 @@ void CairoWidget::Render(const ImVec2& uv0, const ImVec2& uv1,
   draw_func(ctx_->GetCairoObject(), ctx_->GetAspectRatio());
 
   // render cairo content to OpenGL texture
-  GLuint image = ctx_->RenderToGlTexture();
+  uint32_t image = ctx_->RenderToGlTexture();
   ImGui::Image((void*)(intptr_t)image, ImGui::GetContentRegionAvail(), uv0, uv1,
                tint_col, border_col);
 }