ios/glview: fix padding calculation

ios/IJKMediaPlayer/IJKMediaPlayer/ijkmedia/ijksdl/ios/IJKSDLGLView.m

@@ -176,6 +176,7 @@ static void mat4f_LoadOrtho(float left, float right, float bottom, float top, fl
 
     BOOL            _didSetContentMode;
     BOOL            _didRelayoutSubViews;
+    BOOL            _didVerticesChanged;
     BOOL            _didPaddingChanged;
 
     int             _tryLockErrorCount;
@@ -435,10 +436,18 @@ static int g_ijk_gles_queue_spec_key;
 
 - (void)layoutOnDisplayThread
 {
+    int backingWidth  = 0;
+    int backingHeight = 0;
     glBindRenderbuffer(GL_RENDERBUFFER, _renderbuffer);
     [_context renderbufferStorage:GL_RENDERBUFFER fromDrawable:(CAEAGLLayer*)self.layer];
-	glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &_backingWidth);
-    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &_backingHeight);
+	glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &backingWidth);
+    glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &backingHeight);
+
+    if (_backingWidth != backingWidth || _backingHeight != backingHeight) {
+        _backingWidth  = backingWidth;
+        _backingHeight = backingHeight;
+        _didVerticesChanged = YES;
+    }
 
     GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
 	if (status != GL_FRAMEBUFFER_COMPLETE) {
@@ -449,16 +458,12 @@ static int g_ijk_gles_queue_spec_key;
 
         NSLog(@"OK setup GL framebuffer %d:%d", _backingWidth, _backingHeight);
     }
-
-    [self updateVertices];
-    // FIXME: trigger a redisplay on display thread
-    // [self display: nil];
 }
 
 - (void)setContentMode:(UIViewContentMode)contentMode
 {
-    _didSetContentMode = YES;
     [super setContentMode:contentMode];
+    _didSetContentMode = YES;
     if (self->_useRenderQueue && self->_renderQueue) {
         dispatch_async(self->_renderQueue, ^(){
             [self display:nil];
@@ -502,15 +507,26 @@ static int g_ijk_gles_queue_spec_key;
         }
     }
 
-    if (overlay && (_frameWidth  != overlay->w ||
-                    _frameHeight != overlay->h ||
-                    _frameSarNum != overlay->sar_num ||
-                    _frameSarDen != overlay->sar_den)) {
-        _frameWidth  = overlay->w;
-        _frameHeight = overlay->h;
-        _frameSarNum = overlay->sar_num;
-        _frameSarDen = overlay->sar_den;
-        [self updateVertices];
+    if (overlay) {
+        if (_frameWidth  != overlay->w ||
+            _frameHeight != overlay->h ||
+            _frameSarNum != overlay->sar_num ||
+            _frameSarDen != overlay->sar_den) {
+            _frameWidth  = overlay->w;
+            _frameHeight = overlay->h;
+            _frameSarNum = overlay->sar_num;
+            _frameSarDen = overlay->sar_den;
+            _didVerticesChanged = YES;
+        }
+
+        if (!overlay->is_private && overlay->pitches && _frameWidth > 0) {
+            int frameBufferWidth   = overlay->pitches[0] / _bytesPerPixel;
+            int rightPaddingPixels = frameBufferWidth - _frameWidth;
+            if (rightPaddingPixels != _rightPaddingPixels) {
+                _rightPaddingPixels = rightPaddingPixels;
+                _rightPadding       = ((GLfloat)_rightPaddingPixels) / frameBufferWidth;
+            }
+        }
     }
 
     return YES;
@@ -665,19 +681,14 @@ exit:
         return;
     }
 
-    if (overlay && !overlay->is_private && overlay->pitches[0] / _bytesPerPixel > _frameWidth) {
-        _rightPaddingPixels = overlay->pitches[0] / _bytesPerPixel - _frameWidth;
-        _didPaddingChanged = YES;
-    }
-
     if (_didRelayoutSubViews) {
         _didRelayoutSubViews = NO;
         [self layoutOnDisplayThread];
     }
 
-    if (_didSetContentMode || _didPaddingChanged) {
+    if (_didSetContentMode || _didVerticesChanged) {
         _didSetContentMode = NO;
-        _didPaddingChanged = NO;
+        _didVerticesChanged = NO;
         [self updateVertices];
     }
 
@@ -688,17 +699,10 @@ exit:
 	glUseProgram(_program);
 
     if (overlay) {
-        _frameWidth  = overlay->w;
-        _frameHeight = overlay->h;
-        _frameSarNum = overlay->sar_num;
-        _frameSarDen = overlay->sar_den;
         [_renderer render:overlay];
     }
 
     if ([_renderer prepareDisplay]) {
-        if (_frameWidth > 0)
-            _rightPadding = ((GLfloat)_rightPaddingPixels) / _frameWidth;
-
         _texCoords[0] = 0.0f;
         _texCoords[1] = 1.0f;
         _texCoords[2] = 1.0f - _rightPadding;