Fix QGLGlyphCache for Open GL ES (1).

When resizing the font texture the code was using glGetTexImage
which is not available on Open GL ES.
We need to cache the font texture data, and draw the glyphs on
it in addition, so we can copy the data when resizing the texture size.

1 files changed, 20 insertions, 15 deletions

diff --git a/src/opengl/qpaintengine_opengl.cpp b/src/opengl/qpaintengine_opengl.cpp
index 71ed690..0f33cab 100644
--- a/src/opengl/qpaintengine_opengl.cpp
+++ b/src/opengl/qpaintengine_opengl.cpp
@@ -4536,11 +4536,14 @@ struct QGLGlyphCoord {
 };
 
 struct QGLFontTexture {
+    QGLFontTexture() : data(0) { }
+    ~QGLFontTexture() { free(data); }
     int x_offset; // glyph offset within the
     int y_offset;
     GLuint texture;
     int width;
     int height;
+    uchar *data;
 };
 
 typedef QHash<glyph_t, QGLGlyphCoord*>  QGLGlyphHash;
@@ -4563,7 +4566,7 @@ public:
     QGLGlyphCoord *lookup(QFontEngine *, glyph_t);
     void cacheGlyphs(QGLContext *, QFontEngine *, glyph_t *glyphs, int numGlyphs);
     void cleanCache();
-    void allocTexture(int width, int height, GLuint texture);
+    void allocTexture(QGLFontTexture *);
 
 public slots:
     void cleanupContext(const QGLContext *);
@@ -4681,19 +4684,18 @@ void QGLGlyphCache::cleanCache()
     qt_context_cache.clear();
 }
 
-void QGLGlyphCache::allocTexture(int width, int height, GLuint texture)
+void QGLGlyphCache::allocTexture(QGLFontTexture *font_tex)
 {
-    uchar *tex_data = (uchar *) malloc(width*height*2);
-    memset(tex_data, 0, width*height*2);
-    glBindTexture(GL_TEXTURE_2D, texture);
+    font_tex->data = (uchar *) malloc(font_tex->width*font_tex->height*2);
+    memset(font_tex->data, 0, font_tex->width*font_tex->height*2);
+    glBindTexture(GL_TEXTURE_2D, font_tex->texture);
 #ifndef QT_OPENGL_ES
     glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE8_ALPHA8,
-                 width, height, 0, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, tex_data);
+                 font_tex->width, font_tex->height, 0, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, font_tex->data);
 #else
     glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE_ALPHA,
-                 width, height, 0, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, tex_data);
+                 font_tex->width, font_tex->height, 0, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, font_tex->data);
 #endif
-    free(tex_data);
 }
 
 #if 0
@@ -4777,13 +4779,13 @@ void QGLGlyphCache::cacheGlyphs(QGLContext *context, QFontEngine *fontEngine,
         Q_ASSERT(max_tex_size > 0);
         if (tex_width > max_tex_size)
             tex_width = max_tex_size;
-        allocTexture(tex_width, tex_height, font_texture);
         font_tex = new QGLFontTexture;
         font_tex->texture = font_texture;
         font_tex->x_offset = x_margin;
         font_tex->y_offset = y_margin;
         font_tex->width = tex_width;
         font_tex->height = tex_height;
+        allocTexture(font_tex);
 //         qDebug() << "new font tex - width:" << tex_width << "height:"<< tex_height
 //                  << hex << "tex id:" << font_tex->texture << "key:" << font_key << "num cached:" << qt_font_textures.size();
         qt_font_textures.insert(font_key, font_tex);
@@ -4806,21 +4808,19 @@ void QGLGlyphCache::cacheGlyphs(QGLContext *context, QFontEngine *fontEngine,
                 font_tex->y_offset += strip_height;
                 if (font_tex->y_offset >= font_tex->height) {
                     // get hold of the old font texture
-                    uchar *old_tex_data = (uchar *) malloc(font_tex->width*font_tex->height*2);
+                    uchar *old_tex_data = font_tex->data;
                     int old_tex_height = font_tex->height;
-#ifndef QT_OPENGL_ES
-                    glGetTexImage(GL_TEXTURE_2D, 0, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, old_tex_data);
-#endif
 
                     // realloc a larger texture
                     glDeleteTextures(1, &font_tex->texture);
                     glGenTextures(1, &font_tex->texture);
                     font_tex->height = qt_next_power_of_two(font_tex->height + strip_height);
-                    allocTexture(font_tex->width, font_tex->height, font_tex->texture);
+                    allocTexture(font_tex);
 
                     // write back the old texture data
                     glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, font_tex->width, old_tex_height,
                                     GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, old_tex_data);
+                    memcpy(font_tex->data, old_tex_data, font_tex->width*old_tex_height*2);
                     free(old_tex_data);
 
                     // update the texture coords and the y offset for the existing glyphs in
@@ -4868,8 +4868,10 @@ void QGLGlyphCache::cacheGlyphs(QGLContext *context, QFontEngine *fontEngine,
                 }
 #endif
                 glyph_im = glyph_im.convertToFormat(QImage::Format_Indexed8);
+                int cacheLineStart = (font_tex->x_offset + font_tex->y_offset*font_tex->width)*2;
                 for (int y=0; y<glyph_im.height(); ++y) {
                     uchar *s = (uchar *) glyph_im.scanLine(y);
+                    int lineStart = idx;
                     for (int x=0; x<glyph_im.width(); ++x) {
                         uchar alpha = is8BitGray ? *s : qAlpha(glyph_im.color(*s));
                         tex_data[idx] = alpha;
@@ -4879,6 +4881,9 @@ void QGLGlyphCache::cacheGlyphs(QGLContext *context, QFontEngine *fontEngine,
                     }
                     if (glyph_im.width()%2 != 0)
                         idx += 2;
+                    // update cache
+                    memcpy(font_tex->data+cacheLineStart, tex_data+lineStart, glyph_width*2);
+                    cacheLineStart += font_tex->width*2;
                 }
                 glTexSubImage2D(GL_TEXTURE_2D, 0, font_tex->x_offset, font_tex->y_offset,
                                 glyph_width, glyph_im.height(),
@@ -4950,7 +4955,7 @@ void QOpenGLPaintEngine::drawStaticTextItem(QStaticTextItem *textItem)
     glEnableClientState(GL_VERTEX_ARRAY);
     glEnableClientState(GL_TEXTURE_COORD_ARRAY);
     bool antialias = !(textItem->fontEngine()->fontDef.styleStrategy & QFont::NoAntialias)
-				   && (d->matrix.type() > QTransform::TxTranslate);
+                                   && (d->matrix.type() > QTransform::TxTranslate);
     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, antialias ? GL_LINEAR : GL_NEAREST);
     glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, antialias ? GL_LINEAR : GL_NEAREST);