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CGraphicsQ.javaAPI DocphoneME MR2 API (J2ME)4851Wed May 02 18:00:20 BST 2007com.sun.midp.chameleon

CGraphicsQ

public class CGraphicsQ extends Object
Chameleon graphics queue class. This class contains methods to help to better control when, how, and how many pixels actually get blitted from the buffer to the physical display.

Fields Summary
public static final boolean
DEBUG
By turning on "debug" mode, all of Chameleon's graphics engine will output tracing info regarding dirty regions, layer locations, bounds, repaints, etc.
protected Vector
refreshQ
A queue of refresh areas, represented by 4 element arrays
Constructors Summary
public CGraphicsQ()
Construct a new Graphics queue.

    
               
      
        refreshQ = new Vector();
Methods Summary
public java.lang.Object[]getRefreshRegions()
Get the queue of all areas of the screen to be refreshed (blitted to the screen). This method will empty the queue and return its contents. Each element in the array will be a 4 element int[] holding the x, y, w, and h of each refresh region

return
the queue of all areas of the screen to be refreshed, as an array of arrays

        synchronized (refreshQ) {
            Object[] q = new Object[refreshQ.size()];
            refreshQ.copyInto(q);
            refreshQ.removeAllElements();
            return q;
        }
public voidqueueRefresh(int x, int y, int w, int h)
Add the specified region to the queue of areas to be refreshed. That is, the region specified by the given coordinates represents a region that has been repainted and needs to be blitted to the display. The coordinates of the region should be in raw screen coordinates, that is, 0,0 would represent the topleft pixel on the screen.

param
x the 'x' anchor coordinate of the region
param
y the 'y' anchor coordinate of the region
param
w the width of the region
param
h the height of the region

        synchronized (refreshQ) {
            int[] region;
            for (int i = 0; i < refreshQ.size(); i++) {
                region = (int[])refreshQ.elementAt(i);
                
                // We test to see if we already have the dirty region
                if (region[0] == x && region[1] == y &&
                    region[2] == w && region[3] == h)
                {
                    return;
                }

                // We also test to see if the dirty region is wholely
                // contained within another region
                if (x >= region[0] && y >= region[1] &&                
                    (x + w) <= (region[0] + region[1]) && 
                    (y + h) <= (region[1] + region[3])) 
                {
                    return;                    
                }

                // Lastly, we do a special case whereby the region
                // is congruent with a previous region. For instance,
                // when changing screens, the title area will repaint,
                // the body area will repaint, and the soft button
                // area will repaint. All 3 areas are congruent and
                // can be coalesced.
                if (x == region[0] && w == region[2]) {
                    if ((region[1] + region[3]) == y ||
                        (y + h) == region[1]) 
                    {
                        if (region[1] > y) {
                            region[1] = y;
                        }
                        region[3] += h;
                        return;
                    } 
                }
            }
            refreshQ.addElement(new int[] {x, y, w, h});
        }