How to – Fade Algorithms (2)

This is the second article about fade algorithms. In the first article I described the basic algorithm, now I will to introduce you to some advance effects we can do with this basic algorithm.

We will use the algorithm MakeFadeRegionToWhite(…) introduced on the post How to – Fade Algorithms (1) to create a new fade effect. This effect can be used, for example, on an initial screen where we usually show the company’s logo.

To create the background effect, we will use the next new algorithm:

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Method Name
MakeMiddleFadeRegion
Parameters
iWidth	Width of the region that we want to fade
iHeight	Height of the region that we want to fade
iLogoHeight	Height of the logo that will be show
iColor	Color to fade
bMiddleWhite	If the value is true the color on the middle of the screen will be white
Return Value
An int data array with the fade image

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This is the algorithm:


public static int [] MakeMiddleFadeRegion(int iWidth, int iHeight,int iLogoHeight, int iColor, boolean bMiddleWhite)
{

int [] data1 = MakeFadeRegionToWhite(iWidth, (iHeight - iLogoHeight) / 2, iColor, !bMiddleWhite);

int [] data2 = MakeFadeRegionToWhite(iWidth, (iHeight - iLogoHeight) / 2, iColor, bMiddleWhite);

int [] data = new int[iWidth * iHeight];

int iDiff = data.length - data1.length - data2.length;

for (int i =0 ; i < data1.length ;i++)
{
data[i] = data1[i];
}

for (int i = 0 ; i < iDiff ;i++)
{
data[i + data1.length] = 0x00FFFFFF;
}

for (int i =0 ; i < data2.length ;i++)
{
data[i + data1.length + iDiff] = data2[i];
}

return data;

}


Then we have to use this method in a Canvas Object in this way:


public class MyCanvas extends GameCanvas
{
private Image objFadeImage =null;
private Image objLogoImage =null;

public void paint(Graphics g)
{

iViewH = this.getHeight();
iViewW = this.getWidth();

// create the fade background
if (objFadeImage == null)
{
int [] imgData = Utils.MakeMiddleFadeRegion(iViewW, iViewH,54, 0xd30007,true);
objFadeImage = Image.createRGBImage(imgData, iViewW, iViewH, true);
}

// load the logo
if (objLogoImage == null)
{
try {
objLogoImage = Image.createImage("/res/Logo_150_53.png");
} catch (IOException ex) {
ex.printStackTrace();
}
}

// draw fade background
g.drawImage(objFadeImage,
0,
0,
Graphics.LEFT | Graphics.TOP );

// draw logo
if (objLogoImage != null)
g.drawImage(objLogoImage,
(int)iViewW / 2,
(int)iViewH / 2,
Graphics.VCENTER | Graphics.HCENTER );

}
}