我尝试使用Canvas更改形状和文本交叉的颜色。 我有2个形状和1个不同颜色的文字。
没有任何PorterDuffXfermode
和PorterDuffColorFilter
模式添加到任何绘画中。我希望交叉形状是特定颜色,例如白色,文本红色或白色,如下图所示。
在我的示例中,文本位于底部,圆圈中间和矩形上方,但它无关紧要,我只想弄清楚它是如何工作的,以及如何将交叉点设置为特定颜色。
正如您在此图片中看到的那样背景为黑色,圆圈为白色,文字为黑色。当圆圈重叠时,圆圈的交点变为黑色,文本的重叠部分变为白色。
我可以用
实现这一目标canvas.drawColor(Color.TRANSPARENT, Mode.CLEAR);
paint.setXfermode(new PorterDuffXfermode(Mode.SRC_OUT));
如果圆形和矩形都是白色而背景是黑色。当我将背景颜色更改为任何其他颜色时,文本不可见,形状为黑色。
答案 0 :(得分:7)
Android Canvas改变形状和文本交集的颜色
和
“如果圆形和矩形都是白色,背景是黑色。 当我将背景颜色更改为任何其他颜色时,文字不可见,形状为黑色。“
(1)是的,我们可以PorterDuff.Mode
(Mode.ADD
):
PorterDuff.Mode mode = Mode.ADD;
(2)Canvas
背景必须为transparent
才能使compositing
生效。
如果您需要任何其他背景颜色,那么我们需要在单独 Canvas
上执行合成。
然后我们将绘图复制到原始Canvas
。
“我也想知道如何在this image”
中获得类似的结果
以下是代码输出(PorterDuff
决定混合颜色; O():
(Q1 :)“可以将圆形,矩形和文本的重叠部分设置为 具体的颜色?“
@Override
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
Paint paint = new Paint();
Paint paintClear = new Paint();
TextPaint textPaint = new TextPaint();
int width = getWidth();
int height = getHeight();
int x = 100;
int y = 100;
int radius = 100;
PorterDuff.Mode mode = Mode.ADD; // mode Mode.ADD
paintClear.setStyle(Style.FILL);
paint.setStyle(Style.FILL);
textPaint.setAntiAlias(true);
textPaint.setTextSize(100 * getResources().getDisplayMetrics().density);
textPaint.setColor(Color.GREEN);
textPaint.setStrokeWidth(3);
// ** clear canvas backgound to white**
paintClear.setColor(Color.WHITE);
canvas.drawPaint(paintClear);
//canvas.save();
Bitmap compositeBitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
Canvas compositeCanvas = new Canvas(compositeBitmap);
paintClear.setColor(Color.TRANSPARENT);
compositeCanvas.drawPaint(paintClear);
// ** draw destination circle in red **
paint.setColor(Color.RED);
compositeCanvas.drawCircle(x+100, y+100, radius, paint);
// ** set Xfermode **
paint.setXfermode(new PorterDuffXfermode(mode));
textPaint.setXfermode(new PorterDuffXfermode(mode));
// ** draw source circle in blue **
paint.setColor(Color.BLUE);
compositeCanvas.drawCircle(x-0, y-0, radius, paint);
// ** draw text in Green **
compositeCanvas.save();
compositeCanvas.rotate(-45, x, y+150);
compositeCanvas.drawText("- 65,6", x, y+150, textPaint);
compositeCanvas.restore();
//copy compositeCanvas to canvas
canvas.drawBitmap(compositeBitmap, 0, 0, null);
//canvas.restore();
}//onDraw
使用RectF包含并交叉:
public Rect mBound = new Rect(0 , 0 , 10 , 10);
public RectF a1 = new Rect(0f , 0f , 10f, 10f);
public RectF b1 = new Rect(5f , 5f , 20f, 20f);
public RectF c1 = new Rect(30f, 30f, 40f, 40f);
int boolean hit = false;
int boolean intersect = false;
hit = hitTest(20,15); // returns false
hit = hitTest(5,5); // returns true
intersect = intersectsTest(a1,b1);// returns true
intersect = intersectsTest(a1,c1);// returns false
public boolean hitTest(int x, int y)
{
return mBound.contains(x, y);
}//
// Returns true if the two specified rectangles intersect
public boolean intersectsTest(RectF a, RectF b)
{
return intersects ( a, b);
}//
你表示你想了解更多关于彩色绘图的信息,这里有一些我玩过的东西。
setColorFilter
和ColorMatrixColorFilter
的实验:
textPaint.setColorFilter(new ColorMatrixColorFilter(getColorMatrix5()));//custom 5
//custom 5
private ColorMatrix getColorMatrix5()
{
ColorMatrix colorMatrix = new ColorMatrix();
colorMatrix.setSaturation(0);//make it greyscale
ColorMatrix blueMatrix = new ColorMatrix(new float[] {
0, 0, 0, 0, 0, // red
0, 0, 0, 0, 0, // green
1, 1, 1, 1, 1, // blue
1, 1, 1, 1, 1 // alpha
});
// Convert, then scale and clamp
colorMatrix.postConcat(blueMatrix);
return colorMatrix;
}//getColorMatrix1
PorterDuff
听起来你需要Custom PorterDuff
。这里有一些代码可以让您了解如何编写一个代码(Android
使用C++
编写的库。)
public class MyPorterDuffMode
{
public Bitmap applyOverlayMode(Bitmap srcBmp, Bitmap destBmp)
{
int width = srcBmp.getWidth();
int height = srcBmp.getHeight();
int srcPixels[] = new int[width * height];
int destPixels[] = new int[width * height];
int resultPixels[] = new int[width * height];
int aS = 0, rS = 0, gS = 0, bS = 0;
int rgbS = 0;
int aD = 0, rD = 0, gD = 0, bD = 0;
int rgbD = 0;
try
{
srcBmp.getPixels(srcPixels, 0, width, 0, 0, width, height);
destBmp.getPixels(destPixels, 0, width, 0, 0, width, height);
srcBmp.recycle();
destBmp.recycle();
}
catch(IllegalArgumentException e)
{
}
catch(ArrayIndexOutOfBoundsException e)
{
}
for(int y = 0; y < height; y++)
{
for(int x = 0; x < width; x++)
{
rgbS = srcPixels[y*width + x];
aS = (rgbS >> 24) & 0xff;
rS = (rgbS >> 16) & 0xff;
gS = (rgbS >> 8) & 0xff;
bS = (rgbS ) & 0xff;
rgbD = destPixels[y*width + x];
aD = ((rgbD >> 24) & 0xff);
rD = (rgbD >> 16) & 0xff;
gD = (rgbD >> 8) & 0xff;
bD = (rgbD ) & 0xff;
//overlay-mode
rS = overlay_byte(rD, rS, aS, aD);
gS = overlay_byte(gD, gS, aS, aD);
bS = overlay_byte(bD, bS, aS, aD);
aS = aS + aD - Math.round((aS * aD)/255f);
resultPixels[y*width + x] = ((int)aS << 24) | ((int)rS << 16) | ((int)gS << 8) | (int)bS;
}
}
return Bitmap.createBitmap(resultPixels, width, height, srcBmp.getConfig());
}
// kOverlay_Mode
int overlay_byte(int sc, int dc, int sa, int da)
{
int tmp = sc * (255 - da) + dc * (255 - sa);
int rc;
if (2 * dc <= da)
{
rc = 2 * sc * dc;
}
else
{
rc = sa * da - 2 * (da - dc) * (sa - sc);
}
return clamp_div255round(rc + tmp);
}
int clamp_div255round(int prod)
{
if (prod <= 0)
{
return 0;
}
else if (prod >= 255*255)
{
return 255;
}
else
{
return Math.round((float)prod/255);
}
}
}//class MyPorterDuffMode
请参阅PorterDuff,PorterDuff.Mode
,PorterDuffXfermode
,ColorFilter
,ColorMatrix,ColorMatrixColorFilter,PorterDuffColorFilter,{{3} },Canvas
。