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Name

Raster - manipulate color images

Synopsis

#include <ivplus/raster.h>

Description

Raster is a two dimensional array of pixel values. These pixel values are comprised of red, green, blue and alpha components. Alpha refers to the opacity of a given pixel. The current implementation of alpha is fully opaque (i.e., has a value of 1.0). Rasters can be rendered on the screen using Painter::RasterRect() (see Painter(3X) ). Raster images are initially blank. Images are built up pixel by pixel. Individual pixel values may be queried and set using peek() and poke(). Raster is derived from Resource and has an initial reference count of 0.

Class Hierarchy

Raster->Resource

Constructors

Raster (unsigned long width, unsigned long height);

Creates a raster with the indicated width and height.

Raster(const Raster&)

Creates a copy of the given Raster.

Public Operations

virtual void flush() const

Makes all pixels visible.

unsigned int Height () const

Returns the height of the raster.

virtual void peek(unsigned long x, unsigned long y, ColorIntensity& red, ColorIntensity& green, ColorIntensity& blue, float& alpha) const

Returns the component values of the pixel at <x, y>. A ColorIntensity of 1.0 means that component is fully on, 0.0 means fully off. ColorIntensity is defined in <ivplus/color.h>.

virtual void poke(unsigned long x, unsigned long y, ColorIntensity red, ColorIntensity green, ColorIntensity blue, float alpha)

Sets the component values of the pixel at <x, y>. A ColorIntensity of 1.0 means that component is fully on, 0.0 means fully off. ColorIntensity is defined in <ivplus/color.h>.

unsigned int Width () const

Returns the width of the raster.

Protected Operations

None.

X Resources

None.

Examples


//                            Raster Example
#include <ivplus/bitmap.h>
#include <ivplus/box.h>
#include <ivplus/frame.h>
#include <ivplus/interactor.h>
#include <ivplus/message.h>
#include <ivplus/painter.h>
#include <ivplus/raster.h>
#include <ivplus/shape.h>
#include <ivplus/world.h>
class RasterRenderer : public Interactor {
public:
   RasterRenderer(Raster* r);
protected:
   virtual void Redraw(IntCoord, IntCoord, IntCoord, IntCoord);
   virtual void Reconfig();
private:
   int width, height;
   Raster* raster;
};
// Cache the important values.
RasterRenderer::RasterRenderer(Raster* r)
{
   raster = r;
   width = r->Width();
   height = r->Height();
}
// A RasterRenderer draws the indicated Raster in the middle
// of the canvas.
void RasterRenderer::Redraw(IntCoord left, IntCoord bottom,
                            IntCoord right, IntCoord top)
{
   output->ClearRect(canvas, left, bottom, right, top);
   int rx = (xmax - width)/2;
   int ry = (ymax - height)/2;
   output->RasterRect(canvas, rx, ry, raster);
}
// Make sure there’s enough room to draw the Raster.
void RasterRenderer::Reconfig()
{
   shape->width = width;
   shape->height = height;
   shape->Rigid(0, hfil, 0, vfil);
}
int main(int argc, char **argv)
{
   // Create the world to get the connection with the display.
   World* world = new World("MyApp", argc, argv);
  
   // using "/usr/lib/X11/bitmaps/HPlogo.bm"
   const int HPlogo_width=46;
   const int HPlogo_height=34;
   static char HPlogo_bits[] = {
   0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0xe0, 0xff, 0x79, 0xfe, 0xff, 0xc1,
   0xf8, 0xff, 0x39, 0xfe, 0xff, 0xc7, 0xfc, 0xff, 0x3d, 0xfc, 0xff, 0xcf,
   0xfc, 0xff, 0x3c, 0xe0, 0xff, 0xcf, 0xfe, 0x7f, 0x1c, 0x80, 0xff, 0xdf,
   0xfe, 0x3f, 0x1c, 0x00, 0xff, 0xdf, 0xfe, 0x1f, 0x1e, 0x00, 0xfe, 0xdf,
   0xfe, 0x0f, 0x1e, 0x00, 0xfc, 0xdf, 0xfe, 0x07, 0x0e, 0x00, 0xf8, 0xdf,
   0xfe, 0x07, 0x0f, 0x00, 0xf8, 0xdf, 0xfe, 0x03, 0x7f, 0xfc, 0xf1, 0xdf,
   0xfe, 0x03, 0xff, 0xfc, 0xf3, 0xdf, 0xfe, 0x03, 0xff, 0xfc, 0xf3, 0xdf,
   0xfe, 0x81, 0xf7, 0xde, 0xe3, 0xdf, 0xfe, 0x81, 0x77, 0xde, 0xe1, 0xdf,
   0xfe, 0x81, 0x73, 0xce, 0xe1, 0xdf, 0xfe, 0xc1, 0x7b, 0xee, 0xe1, 0xdf,
   0xfe, 0xc1, 0x7b, 0xef, 0xe1, 0xdf, 0xfe, 0xc1, 0x3b, 0xe7, 0xe0, 0xdf,
   0xfe, 0xc3, 0x39, 0xff, 0xf0, 0xdf, 0xfe, 0xe3, 0xbd, 0xff, 0xf0, 0xdf,
   0xfe, 0xe3, 0xbd, 0x7f, 0xf0, 0xdf, 0xfe, 0x07, 0x80, 0x03, 0xf8, 0xdf,
   0xfe, 0x07, 0x80, 0x03, 0xf8, 0xdf, 0xfe, 0x0f, 0xc0, 0x03, 0xfc, 0xdf,
   0xfe, 0x1f, 0xc0, 0x03, 0xfe, 0xdf, 0xfe, 0x3f, 0xc0, 0x01, 0xff, 0xdf,
   0xfe, 0x7f, 0xc0, 0x81, 0xff, 0xdf, 0xfc, 0xff, 0xe1, 0xe1, 0xff, 0xcf,
   0xfc, 0xff, 0xe7, 0xfc, 0xff, 0xcf, 0xf8, 0xff, 0xe7, 0xfc, 0xff, 0xc7,
   0xe0, 0xff, 0xf3, 0xfc, 0xff, 0xc1, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0
   };
   // Create a Bitmap from the data above.
   Bitmap* bm = new Bitmap(HPlogo_bits, HPlogo_width, HPlogo_height);
   // Create a Raster based on the Bitmap above, twice its size.
   Raster* rast = new Raster(2 * HPlogo_width, 2 * HPlogo_height);
   // Copy the bitmap into the raster, scaling and "colorizing" it as we
go.
   for (int x = 0; x < HPlogo_width; x++) {
      for (int y = 0; y < HPlogo_height; y++) {
         ColorIntensity r = (float)x/(float)HPlogo_width;
         ColorIntensity g = (float)y/(float)HPlogo_height;
         ColorIntensity b = 1.0;
         static const float alpha = 1.0;
         if (bm->peek(x,y)) {
            r = 0.0;
            g = 0.0;
         } else {
            b = 0.0;
         }
         // Color the block of 4 adjacent pixels.
         rast->poke(2 * x,     2 * y,     r, g, b, alpha);
         rast->poke(2 * x + 1, 2 * y,     r, g, b, alpha);
         rast->poke(2 * x,     2 * y + 1, r, g, b, alpha);
         rast->poke(2 * x + 1, 2 * y + 1, r, g, b, alpha);
      }
   }
   // Create a RasterRenderer to draw it.
   RasterRenderer* hplogo = new RasterRenderer(rast);
   // Map the window.
   world->InsertApplication(new Frame(hplogo, 2, BevelOut));
   // Enter the event loop.
   world->Run();
   return 0;
}

Files


raster.h

See Also

Painter(3X) , Resource(3X) .

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