[vtk-developers] 2D DrawImage() API

[Eric E. Monson]

Just a little update. So far a simple change like this has worked and been very useful for me (sorry to just send a diff in the email, but it seemed like the clearest way to get across my idea):

diff --git a/Charts/vtkContext2D.cxx b/Charts/vtkContext2D.cxx
index b97f84d..ae36d2f 100644
--- a/Charts/vtkContext2D.cxx
+++ b/Charts/vtkContext2D.cxx
@@ -493,10 +493,10 @@ void vtkContext2D::ComputeStringBounds(const char *string, float bounds[4])
 }
 
 //-----------------------------------------------------------------------------
-void vtkContext2D::DrawImage(float x, float y, vtkImageData *image)
+void vtkContext2D::DrawImage(float x, float y, float s, vtkImageData *image)
 {
   float p[] = { x, y };
-  this->Device->DrawImage(&p[0], 1, image);
+  this->Device->DrawImage(&p[0], s, image);
 }
 
 //-----------------------------------------------------------------------------
diff --git a/Charts/vtkContext2D.h b/Charts/vtkContext2D.h
index b818520..ecf3314 100644
--- a/Charts/vtkContext2D.h
+++ b/Charts/vtkContext2D.h
@@ -200,7 +200,7 @@ public:
 
   // Description:
   // Draw the supplied image at the given x, y location (bottom corner).
-  void DrawImage(float x, float y, vtkImageData *image);
+  void DrawImage(float x, float y, float s, vtkImageData *image);
 
 //BTX
   // Description:
diff --git a/Charts/vtkContextDevice2D.h b/Charts/vtkContextDevice2D.h
index 803ea36..c245590 100644
--- a/Charts/vtkContextDevice2D.h
+++ b/Charts/vtkContextDevice2D.h
@@ -101,7 +101,7 @@ public:
 
   // Description:
   // Draw the supplied image at the given x, y (p[0], p[1]) location(s) (bottom corner).
-  virtual void DrawImage(float *, int , vtkImageData *) {;}
+  virtual void DrawImage(float *, float, vtkImageData *) {;}
 
   // Description:
   // Set the color for the device using unsigned char of length 4, RGBA.
diff --git a/Charts/vtkImageItem.cxx b/Charts/vtkImageItem.cxx
index 166ec91..58b07fd 100644
--- a/Charts/vtkImageItem.cxx
+++ b/Charts/vtkImageItem.cxx
@@ -74,7 +74,7 @@ bool vtkImageItem::Paint(vtkContext2D *painter)
   if (this->Image)
     {
     // Draw our image in the bottom left corner of the item
-    painter->DrawImage(this->Dimensions[0]+10, this->Dimensions[1]+10, this->Image);
+    painter->DrawImage(this->Dimensions[0]+10, this->Dimensions[1]+10, 1.0, this->Image);
     }
 
   if (this->MouseOver && this->Label)
diff --git a/Charts/vtkOpenGLContextDevice2D.cxx b/Charts/vtkOpenGLContextDevice2D.cxx
index 6bed52d..77a9d56 100644
--- a/Charts/vtkOpenGLContextDevice2D.cxx
+++ b/Charts/vtkOpenGLContextDevice2D.cxx
@@ -672,16 +672,16 @@ void vtkOpenGLContextDevice2D::ComputeStringBounds(const vtkStdString &string,
 }
 
 //-----------------------------------------------------------------------------
-void vtkOpenGLContextDevice2D::DrawImage(float *p, int, vtkImageData *image)
+void vtkOpenGLContextDevice2D::DrawImage(float *p, float s, vtkImageData *image)
 {
   vtkTexture *tex =vtkTexture::New();
   tex->SetInput(image);
   tex->Render(this->Renderer);
   int *extent = image->GetExtent();
   float points[] = { p[0]          , p[1],
-                     p[0]+extent[1], p[1],
-                     p[0]+extent[1], p[1]+extent[3],
-                     p[0]          , p[1]+extent[3] };
+                     p[0]+s*extent[1], p[1],
+                     p[0]+s*extent[1], p[1]+s*extent[3],
+                     p[0]          , p[1]+s*extent[3] };
 
   float texCoord[] = { 0.0, 0.0,
                        1.0, 0.0,
diff --git a/Charts/vtkOpenGLContextDevice2D.h b/Charts/vtkOpenGLContextDevice2D.h
index 531d1db..3cae172 100644
--- a/Charts/vtkOpenGLContextDevice2D.h
+++ b/Charts/vtkOpenGLContextDevice2D.h
@@ -104,7 +104,7 @@ public:
 
   // Description:
   // Draw the supplied image at the given x, y (p[0], p[1]) location(s) (bottom corner).
-  virtual void DrawImage(float *p, int n, vtkImageData *image);
+  virtual void DrawImage(float *p, float s, vtkImageData *image);
 
   // Description:
   // Set the color for the device using unsigned char of length 4, RGBA.


On Jun 7, 2010, at 3:03 PM, Eric E. Monson wrote:

> Hey,
> 
> I'm working on some customizations of the Charts, and it requires drawing images with the 2D API. The problem I'm running into is that with DrawImage() in its various forms there is no easy way to scale the image for display, and it limits the usability quite a bit (e.g. if I have image data that have very large or small extents I have to resample the image before drawing it to make it a reasonable size for viewing).
> 
> Do you think it would be possible to change the vtkOpenGLContextDevice2D::DrawImage() to include a floating point scaling factor? (Or, I guess, some sort of width, height pixel dimensions for the display size, if you prefer, but I personally like keeping the original aspect ratio.) From what I can see, this would require small changes in:
> 
> vtkContext2D.cxx
> vtkContext2D.h
> vtkContextDevice2D.h
> vtkImageItem.cxx
> vtkOpenGLContextDevice2D.cxx
> vtkOpenGLContextDevice2D.h
> 
> There isn't a lot in the public repository that uses image drawing, but I don't know how much you guys are doing with it behind the scenes, so I don't know how much of a pain it would be to change the API now.
> 
> Let me know what you think. I could supply a patch after I experiment a bit more if you think it's reasonable to make this kind of change.
> 
> Thanks,
> -Eric
>