Fl_OpenGL_Graphics_Driver: create file Fl_OpenGL_Graphics_Driver_image.cxx

src/CMakeLists.txt

@@ -488,6 +488,7 @@ set(GL_DRIVER_FILES
   drivers/OpenGL/Fl_OpenGL_Graphics_Driver_line_style.cxx
   drivers/OpenGL/Fl_OpenGL_Graphics_Driver_rect.cxx
   drivers/OpenGL/Fl_OpenGL_Graphics_Driver_vertex.cxx
+  drivers/OpenGL/Fl_OpenGL_Graphics_Driver_image.cxx
 )
 if(FLTK_USE_WAYLAND)
   set(GL_DRIVER_FILES ${GL_DRIVER_FILES} drivers/Wayland/Fl_Wayland_Gl_Window_Driver.cxx)

src/drivers/OpenGL/Fl_OpenGL_Graphics_Driver_font.cxx

@@ -1,5 +1,5 @@
 //
-// Standard X11 font selection code for the Fast Light Tool Kit (FLTK).
+// Support for drawing text to Fl_Gl_Window for the Fast Light Tool Kit (FLTK).
 //
 // Copyright 1998-2016 by Bill Spitzak and others.
 //
@@ -29,7 +29,6 @@
 #include "Fl_OpenGL_Graphics_Driver.H"
 #include <FL/gl.h>
 #include <FL/Fl_Gl_Window.H>
-#include <FL/Fl_RGB_Image.H>
 #include <FL/Fl.H>
 #include <FL/fl_draw.H>
 
@@ -224,114 +223,4 @@ void Fl_OpenGL_Graphics_Driver::text_extents(const char *str, int n, int& dx, in
   Fl_Surface_Device::pop_current();
 }
 
-
-void Fl_OpenGL_Graphics_Driver::cache_size(Fl_Image* img, int &width, int &height) {
-  width *= pixels_per_unit_; // useful at least for Fl_SVG_Image's
-  height *= pixels_per_unit_;
-}
-
-
-#ifndef GL_TEXTURE_RECTANGLE_ARB
-#  define GL_TEXTURE_RECTANGLE_ARB 0x84F5
-#endif
-#ifndef GL_UNSIGNED_INT_8_8_8_8_REV
-#  define GL_UNSIGNED_INT_8_8_8_8_REV 0x8367
-#endif
-
-static GLuint compute_texture_rectangle(Fl_RGB_Image *rgb)
-{
-  GLuint texName;
-  glGenTextures(1, &texName);
-  // save GL parameters GL_UNPACK_ROW_LENGTH and GL_UNPACK_ALIGNMENT
-  GLint row_length, alignment;
-  glGetIntegerv(GL_UNPACK_ROW_LENGTH, &row_length);
-  glGetIntegerv(GL_UNPACK_ALIGNMENT, &alignment);
-  // put the bitmap in a texture
-  glPushAttrib(GL_TEXTURE_BIT);
-  glBindTexture (GL_TEXTURE_RECTANGLE_ARB, texName);
-  glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-  glPixelStorei(GL_UNPACK_ROW_LENGTH, (rgb->ld() ? rgb->ld() / rgb->d() : rgb->data_w()));
-  glPixelStorei(GL_UNPACK_ALIGNMENT, (rgb->d() == 3 ? 1 : 4));
-  glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, (rgb->d() == 3 ? GL_RGB : GL_RGBA8),
-               rgb->data_w(), rgb->data_h(), 0,
-               (rgb->d() == 3 ? GL_RGB : GL_RGBA),
-               (rgb->d() == 3 ? GL_UNSIGNED_BYTE : GL_UNSIGNED_INT_8_8_8_8_REV),
-               rgb->array);
-  glPopAttrib();
-  // restore saved GL parameters
-  glPixelStorei(GL_UNPACK_ROW_LENGTH, row_length);
-  glPixelStorei(GL_UNPACK_ALIGNMENT, alignment);
-  return texName;
-}
-
-
-void Fl_OpenGL_Graphics_Driver::draw_rgb(Fl_RGB_Image *img,
-                                         int XP, int YP, int WP, int HP, int cx, int cy) {
-  int X, Y, W, H;
-  // Don't draw an empty image. Gray-scale image drawing not implemented yet.
-  if (!img->d() || !img->array || img->d() < 3) {
-    Fl_Graphics_Driver::draw_empty(img, XP, YP);
-    return;
-  }
-  if (start_image(img, XP, YP, WP, HP, cx, cy, X, Y, W, H)) {
-    return;
-  }
-  Fl_RGB_Image *partial_rgb = NULL;
-  if (cx || cy || W < img->w() || H < img->h()) { // Partial image drawing.
-    int d = img->d();
-    int ld = d * img->data_w();
-    float sx = img->data_w() / float(img->w()), sy = img->data_h() / float(img->h());
-    cx *= sx; cy *= sy;
-    partial_rgb = new Fl_RGB_Image(img->array + cy * ld + cx * d, W * sx, H * sy, d, ld);
-    img = partial_rgb;
-  }
-  GLuint texName = compute_texture_rectangle(img);
-  // GL_TRANSFORM_BIT for GL_PROJECTION
-  // GL_TEXTURE_BIT for GL_TEXTURE_RECTANGLE_ARB
-  glPushAttrib(GL_TRANSFORM_BIT | GL_TEXTURE_BIT /*|GL_COLOR_BUFFER_BIT*/);
-  //setup matrices
-  glMatrixMode(GL_PROJECTION);
-  glPushMatrix();
-  glLoadIdentity();
-  glColor4ub(0xff, 0xff, 0xff, 0xff); // the color drawn through the texture seen as a kind of mask
-
-  float winw = Fl_Window::current()->as_gl_window()->pixel_w();
-  float winh = Fl_Window::current()->as_gl_window()->pixel_h();
-
-  float R = 2;
-  glScalef(R/winw, R/winh, 1.0f);
-  glTranslatef(-winw/R, -winh/R, 0.0f);
-  float s = Fl_Window::current()->as_gl_window()->pixels_per_unit();
-  int HH = s * H, WW = s * W;
-  float ox = s * X;
-  float oy = winh - s * Y;
-  glEnable(GL_TEXTURE_RECTANGLE_ARB);
-  glBindTexture(GL_TEXTURE_RECTANGLE_ARB, texName);
-  //write the texture on screen
-  glBegin(GL_QUADS);
-  glTexCoord2f(0.0f, 0.0f); // draw lower left in world coordinates
-  glVertex2f(ox, oy);
-  glTexCoord2f(0.0f, (GLfloat)img->data_h()); // draw upper left in world coordinates
-  glVertex2f(ox, oy - HH);
-  glTexCoord2f((GLfloat)img->data_w(), (GLfloat)img->data_h()); // draw upper right in world coordinates
-  glVertex2f(ox + WW, oy - HH);
-  glTexCoord2f((GLfloat)img->data_w(), 0.0f); // draw lower right in world coordinates
-  glVertex2f(ox + WW, oy);
-  glEnd();
-  glDeleteTextures(1, &texName);
-  color(color()); // reset current color
-  // reset original matrices
-  glMatrixMode(GL_PROJECTION);
-  glPopMatrix();
-  glPopAttrib(); // GL_TRANSFORM_BIT | GL_TEXTURE_BIT
-  if (partial_rgb) delete partial_rgb;
-}
-
-
-void Fl_OpenGL_Graphics_Driver::draw_pixmap(Fl_Pixmap *img,
-                                            int XP, int YP, int WP, int HP, int cx, int cy) {
-  Fl_RGB_Image rgb(img);
-  draw_rgb(&rgb, XP, YP, WP, HP, cx, cy);
-}
-
 #endif

src/drivers/OpenGL/Fl_OpenGL_Graphics_Driver_image.cxx

@@ -0,0 +1,131 @@
+//
+// Support for drawing images to Fl_Gl_Window for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 2026 by Bill Spitzak and others.
+//
+// This library is free software. Distribution and use rights are outlined in
+// the file "COPYING" which should have been included with this file.  If this
+// file is missing or damaged, see the license at:
+//
+//     https://www.fltk.org/COPYING.php
+//
+// Please see the following page on how to report bugs and issues:
+//
+//     https://www.fltk.org/bugs.php
+//
+
+#include "Fl_OpenGL_Graphics_Driver.H"
+#include <FL/gl.h>
+#include <FL/Fl_Gl_Window.H>
+#include <FL/Fl_RGB_Image.H>
+#include <FL/Fl.H>
+
+
+void Fl_OpenGL_Graphics_Driver::cache_size(Fl_Image* img, int &width, int &height) {
+  width *= pixels_per_unit_; // useful at least for Fl_SVG_Image's
+  height *= pixels_per_unit_;
+}
+
+
+#ifndef GL_TEXTURE_RECTANGLE_ARB
+#  define GL_TEXTURE_RECTANGLE_ARB 0x84F5
+#endif
+#ifndef GL_UNSIGNED_INT_8_8_8_8_REV
+#  define GL_UNSIGNED_INT_8_8_8_8_REV 0x8367
+#endif
+
+static GLuint compute_texture_rectangle(Fl_RGB_Image *rgb)
+{
+  GLuint texName;
+  glGenTextures(1, &texName);
+  // save GL parameters GL_UNPACK_ROW_LENGTH and GL_UNPACK_ALIGNMENT
+  GLint row_length, alignment;
+  glGetIntegerv(GL_UNPACK_ROW_LENGTH, &row_length);
+  glGetIntegerv(GL_UNPACK_ALIGNMENT, &alignment);
+  // put the bitmap in a texture
+  glPushAttrib(GL_TEXTURE_BIT);
+  glBindTexture (GL_TEXTURE_RECTANGLE_ARB, texName);
+  glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glPixelStorei(GL_UNPACK_ROW_LENGTH, (rgb->ld() ? rgb->ld() / rgb->d() : rgb->data_w()));
+  glPixelStorei(GL_UNPACK_ALIGNMENT, (rgb->d() == 3 ? 1 : 4));
+  glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, (rgb->d() == 3 ? GL_RGB : GL_RGBA8),
+               rgb->data_w(), rgb->data_h(), 0,
+               (rgb->d() == 3 ? GL_RGB : GL_RGBA),
+               (rgb->d() == 3 ? GL_UNSIGNED_BYTE : GL_UNSIGNED_INT_8_8_8_8_REV),
+               rgb->array);
+  glPopAttrib();
+  // restore saved GL parameters
+  glPixelStorei(GL_UNPACK_ROW_LENGTH, row_length);
+  glPixelStorei(GL_UNPACK_ALIGNMENT, alignment);
+  return texName;
+}
+
+
+void Fl_OpenGL_Graphics_Driver::draw_rgb(Fl_RGB_Image *img,
+                                         int XP, int YP, int WP, int HP, int cx, int cy) {
+  int X, Y, W, H;
+  // Don't draw an empty image. Gray-scale image drawing not implemented yet.
+  if (!img->d() || !img->array || img->d() < 3) {
+    Fl_Graphics_Driver::draw_empty(img, XP, YP);
+    return;
+  }
+  if (start_image(img, XP, YP, WP, HP, cx, cy, X, Y, W, H)) {
+    return;
+  }
+  Fl_RGB_Image *partial_rgb = NULL;
+  if (cx || cy || W < img->w() || H < img->h()) { // Partial image drawing.
+    int d = img->d();
+    int ld = d * img->data_w();
+    float sx = img->data_w() / float(img->w()), sy = img->data_h() / float(img->h());
+    cx *= sx; cy *= sy;
+    partial_rgb = new Fl_RGB_Image(img->array + cy * ld + cx * d, W * sx, H * sy, d, ld);
+    img = partial_rgb;
+  }
+  GLuint texName = compute_texture_rectangle(img);
+  // GL_TRANSFORM_BIT for GL_PROJECTION
+  // GL_TEXTURE_BIT for GL_TEXTURE_RECTANGLE_ARB
+  glPushAttrib(GL_TRANSFORM_BIT | GL_TEXTURE_BIT);
+  //setup matrices
+  glMatrixMode(GL_PROJECTION);
+  glPushMatrix();
+  glLoadIdentity();
+  glColor4ub(0xff, 0xff, 0xff, 0xff); // the color drawn through the texture seen as a kind of mask
+
+  float winw = Fl_Window::current()->as_gl_window()->pixel_w();
+  float winh = Fl_Window::current()->as_gl_window()->pixel_h();
+
+  float R = 2;
+  glScalef(R/winw, R/winh, 1.0f);
+  glTranslatef(-winw/R, -winh/R, 0.0f);
+  float s = Fl_Window::current()->as_gl_window()->pixels_per_unit();
+  int HH = s * H, WW = s * W;
+  float ox = s * X;
+  float oy = winh - s * Y;
+  glEnable(GL_TEXTURE_RECTANGLE_ARB);
+  glBindTexture(GL_TEXTURE_RECTANGLE_ARB, texName);
+  //write the texture on screen
+  glBegin(GL_QUADS);
+  glTexCoord2f(0.0f, 0.0f); // draw lower left in world coordinates
+  glVertex2f(ox, oy);
+  glTexCoord2f(0.0f, (GLfloat)img->data_h()); // draw upper left in world coordinates
+  glVertex2f(ox, oy - HH);
+  glTexCoord2f((GLfloat)img->data_w(), (GLfloat)img->data_h()); // draw upper right in world coordinates
+  glVertex2f(ox + WW, oy - HH);
+  glTexCoord2f((GLfloat)img->data_w(), 0.0f); // draw lower right in world coordinates
+  glVertex2f(ox + WW, oy);
+  glEnd();
+  glDeleteTextures(1, &texName);
+  color(color()); // reset current color
+  // reset original matrices
+  glMatrixMode(GL_PROJECTION);
+  glPopMatrix();
+  glPopAttrib(); // GL_TRANSFORM_BIT | GL_TEXTURE_BIT
+  if (partial_rgb) delete partial_rgb;
+}
+
+
+void Fl_OpenGL_Graphics_Driver::draw_pixmap(Fl_Pixmap *img,
+                                            int XP, int YP, int WP, int HP, int cx, int cy) {
+  Fl_RGB_Image rgb(img);
+  draw_rgb(&rgb, XP, YP, WP, HP, cx, cy);
+}

test/gl_image.cxx

@@ -23,7 +23,7 @@
 class image_background_box : public Fl_Widget {
 public:
   image_background_box(int x, int y, int w, int h) : Fl_Widget(x, y, w, h, NULL) {}
-  void draw() {
+  void draw() override {
     gl_color(FL_WHITE);
     gl_rectf(x(), y(), w(), h());
     gl_color(color());
@@ -94,7 +94,7 @@ void chooser_cb(Fl_Widget *, Gl_Image_Window *mainwin) {
   char *fname = fl_file_chooser("select image file", "*.{png,jpg,gif,svg,svgz}", NULL, 0);
   if (fname) {
     Fl_Shared_Image *shared = Fl_Shared_Image::get(fname);
-    if (!shared->fail()) {
+    if (shared && !shared->fail()) {
       mainwin->copy_label(fname);
       mainwin->set_image(shared);
     }