Problem with Translate mathod

[chandu_bgm]

Hello...

I am try to develop some game where I need to move the background Image Please help me
I have written this code but this is not working properly...
I mean I am not getting any errors but the backgroud Image is not moving as I want it to move.

please help me....

Thankz in Advance
Chandu



==============================================
import javax.microedition.lcdui.*;



public class MyCanvas extends javax.microedition.lcdui.Canvas implements Runnable {
Image offImage,bgImage; // An Image for double buffering.
Graphics offGraphics; // A global variable for graphics.
int w,h; //Screen-width and height
Thread thread; // The Thread
int blackCol= 0x00000000;
int whiteCol= 0x00ffffff;
boolean forceTerminate=false;
static int X1,Y1;

public MyCanvas() {
w = 120;
h = 120;
offImage = Image.createImage(150,150); // Prepare image for double buffer.
offGraphics = offImage.getGraphics(); // Prepare graphics for double buffer.
offGraphics.setClip(0, 0, w, h); // Set clipping area.

}

protected void paint(Graphics g) {
g.drawImage(offImage,0,0,20);
g.translate(X1,Y1);
}

public void doStart() {
thread = new Thread(this);
// Prepare the thraed...
thread.start();
// Go...
}


public void run(){
loadImagies();
while(!forceTerminate) {
//Repeat for ever
offGraphics.drawImage(bgImage,0,0,20);
repaint();
serviceRepaints();
//System.out.println("XXX");
}




}
void loadImagies(){
try{
bgImage=Image.createImage("/bgImage.png");
}catch(Exception ex){System.out.println("Error while loading the Image"+ex);}
}

///////////////////////////////////////////////////////////////////////
public void keyPressed(int keyCode)
{
int action = getGameAction(keyCode); // Store the value for the key pressed.
if(action==LEFT || keyCode==KEY_NUM4) //Left Arrow ( move curser to left )
{
X1=X1-50;
// offGraphics.translate(X1,Y1);
System.out.println("X1 --->"+X1);
}
else if(action==RIGHT || keyCode==KEY_NUM6)
//Right Arrow ( move curser to right )
{
X1=X1+50;
//offGraphics.translate(X1,Y1);
System.out.println("X1 --->"+X1);
}
else if(action==UP || keyCode==KEY_NUM2)
//Up Arrow ( move curser to Up)
{
Y1=Y1-50;
// offGraphics.translate(X1,Y1);
System.out.println("Y1 --->"+Y1);
}
else if(action==DOWN || keyCode==KEY_NUM8)
//Down Arrow ( move curser to Down )
{
Y1=Y1+50;
//offGraphics.translate(X1,Y1);
System.out.println("Y1 --->"+Y1);
}
repaint();
serviceRepaints();
}



}

[StingerAJ]

Hello,

as I understand, the method Graphics.translate(...) only translates the coordinate-system of the Graphics-Context, not the content of the screen itself.

To do this, you have to move the anchorpoint of the image relative to the origin of the Graphics-Context.

In your example this would look like this:

protected void paint(Graphics g) {
g.drawImage(offImage,anchorX,anchorY,20);
g.translate(X1,Y1);
}

public void run(){
loadImagies(); 
while(!forceTerminate) {
// NEW: move the anchorpoints in the desired direction
// HERE: scrolling diagonal from topleft to downright
anchorX++; anchorY++;
//Repeat for ever
repaint();
serviceRepaints();
//System.out.println("XXX");
}

I recommend the Helicopter-Example from the Nokia-Documents-Section, its a good start.


I hope I could help,

StingerAJ

[shmoove]

When you start the paint() method you get a fresh graphics context with the coordinate origin at (0,0) every time. You're drawing the image there (at 0,0), and then translating the origin. But the next time paint() is called the origin is back at (0,0). If you want to use translate like this you should do the translating before you draw the image (and each time by a different value).

shmoove

[StingerAJ]

Thx for the info, shmoove.

Greetings,

StingerAJ