一.package com.example.android.apis.content;
1.ReadAsset:从asset目录里读出
2.ResourcesSample：在values的strings.xml里取得string,
以及在非activity里取得方法。
Resources res = context.getResources();
CharSequence cs = res.getText(R.string.styled_text);
3.StyledText:在TextView里直接setText带有styled的字符串<string name="styled_text">Plain, <b>bold</b>, <i>italic</i>, <b><i>bold-italic</i></b></string>
二.package com.example.android.apis.graphics;
1.AlphaBitmap：应用Paint p.setAntiAlias(true);//抗锯齿，如果没有调用这个方法，写上去的字不饱满，不美观，看地不太清楚
下图为p.setAntiAlias(false)效果
下图为p.setAntiAlias(true)效果
1.1 p.setAlpha(0x80);//透明度
1.2 p.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));//14例中FingerPaint:手写板有这个用法
1.3 p.setTextSize(60);//设置字体大小
1.4 p.setTextAlign(Paint.Align.CENTER);//基准线
1.5 InputStream is = context.getResources().openRawResource(//从drawable里的图片转到bitmap
R.drawable.app_sample_code);
mBitmap = BitmapFactory.decodeStream(is);
1.6 mShader = new LinearGradient(0, 0, 100, 70, new int[] { Color.RED,//渐变
Color.GREEN, Color.BLUE }, null, Shader.TileMode.MIRROR);
p.setShader(mShader);
2.AnimateDrawables 把一张照片动起来，类似跑马灯的效果，有三个类AnimateDrawables ，AnimateDrawable，ProxyDrawable
2.1 Drawable dr = context.getResources().getDrawable(R.drawable.beach);//获得Drawable
dr.setBounds(0, 0, dr.getIntrinsicWidth(), dr.getIntrinsicHeight());//设置图的边界，有放大缩小的作用
这是设置为100，100的边界效果
2.2 Animation an = new TranslateAnimation(0, 100, 0, 200);//从0，0点到100，200移动的动画
an.setDuration(2000);//持续时间2秒
an.setRepeatCount(-1);//无限循环
2.3 public void draw(Canvas canvas) {
Drawable dr = getProxy();
if (dr != null) {
int sc = canvas.save();//
Animation anim = mAnimation;
if (anim != null) {
anim.getTransformation(AnimationUtils.currentAnimationTimeMillis()//动起来
mTransformation);//该方法根据当前间 (currentTime) 和 interpolator，计算当前的变换，在 outTransformation 中返回
canvas.concat(mTransformation.getMatrix());//对canvas应用矩阵变换
}
dr.draw(canvas);
canvas.restoreToCount(sc);
}
}
注意：canvas.save();//canvas.restoreToCount(sc);是正对出现的
假设我们将要对canvas进行了一系列的设置，例如旋转，变色等，而又不希望在操作完之后让这些设置影响到后面的绘画。
就需要在设置前先save，使用完之后再restore；带count的恢复，是指直接回复到某个状态
假设我们设置了clip去绘画一张图片的一小部分
一般这么干
canvas.save();
canvas.setclip
canvas.drawBitmap
canvas.restore();
3. Arcs：
3.1 mPaints[0] = new Paint();
mPaints[0].setAntiAlias(true);
mPaints[0].setStyle(Paint.Style.FILL);
mPaints[0].setColor(0x88FF0000);
mUseCenters[0] = false;
mPaints[1] = new Paint(mPaints[0]);
mPaints[1].setColor(0x8800FF00);
mUseCenters[1] = true;
mPaints[2] = new Paint(mPaints[0]);
mPaints[2].setStyle(Paint.Style.STROKE);
mPaints[2].setStrokeWidth(4);
mPaints[2].setColor(0x880000FF);
mUseCenters[2] = false;
3.2 canvas.drawArc(oval, mStart, mSweep, useCenter, paint); //useCenter为是否画中心。mStart起始度数，mSweep跨度
4.BitmapDecode：最下面的国旗是GIF动画
4.1 两种加载图片，再转成bitmap的方法
// now opts.outWidth and opts.outHeight are the dimension of the
// bitmap, even though bm is null
opts.inJustDecodeBounds = false; // this will request the bm
opts.inSampleSize = 4; // scaled down by 4 面试变成1/4大小
bm = BitmapFactory.decodeStream(is, null, opts);
mBitmap = bm;
// decode an image with transparency
is = context.getResources().openRawResource(R.drawable.frog);
mBitmap2 = BitmapFactory.decodeStream(is);
4.2 mBitmap2.getPixels(pixels, 0, w, 0, 0, w, h);//获得mBitmap2的像素颜色值，赋值给pixels，第三个参数为一行的像素数（矩形的宽）
mBitmap3 = Bitmap.createBitmap(pixels, 0, w, w, h,
Bitmap.Config.ARGB_8888);//用上面的pixels颜色数组创建一个Bitmap
4.3 mDrawable = context.getResources().getDrawable(R.drawable.button);
mDrawable.setBounds(150, 20, 300, 100);//设置button9的面积（只有Drawable才有这个方法）
4.4 canvas.drawBitmap(mBitmap4, 210, 170, null); //Bitmap的画法
mDrawable.draw(canvas);//Drawable的画法
4.5 is = context.getResources().openRawResource(R.drawable.animated_gif);//获得GIF动画流
mMovie = Movie.decodeStream(is);//把流转成Movie
//画Movie动画
long now = android.os.SystemClock.uptimeMillis();//当前时间
if (mMovieStart == 0) { // first time
mMovieStart = now;
}
if (mMovie != null) {
int dur = mMovie.duration();//GIF持续时间
if (dur == 0) {
dur = 1000;
}
int relTime = (int) ((now - mMovieStart) % dur);
mMovie.setTime(relTime);
mMovie.draw(canvas, getWidth() - mMovie.width(), getHeight()//画动画，参数为X,Y点
- mMovie.height());
invalidate();//刷新，不停的画
}
5. BitmapMesh：(没看)
5.1 mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.beach); //生成Bitmap
6.BitmapPixels：（没看）
7. CameraPreview：（没看）内容同SDK开发大全中的7.15例
7.1 // Hide the window title.隐藏标题
requestWindowFeature(Window.FEATURE_NO_TITLE);
8. Clipping：
8.1
//定好样式
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setStrokeWidth(6);//画笔的宽
mPaint.setTextSize(16);
mPaint.setTextAlign(Paint.Align.RIGHT);
canvas.drawLine(0, 0, 100, 100, mPaint);//画线
画的线为mPaint指定的宽度
8.2
canvas.save();
canvas.translate(160, 10);
canvas.clipRect(10, 10, 90, 90);
canvas.clipRect(30, 30, 70, 70, Region.Op.DIFFERENCE);
drawScene(canvas);
canvas.restore();
8.3
canvas.save();
canvas.translate(10, 160);
mPath.reset();
canvas.clipPath(mPath); // makes the clip empty
mPath.addCircle(50, 50, 50, Path.Direction.CCW);
canvas.clipPath(mPath, Region.Op.REPLACE);
drawScene(canvas);
canvas.restore();
9. ColorFilters：
9.1
Paint.FontMetrics fm = mPaint.getFontMetrics();//不知道是什么意思？？？？？？
float mPaintTextOffset = (fm.descent + fm.ascent) * 0.5f;
9.2
mColors = new int[] { 0, 0xCC0000FF, 0x880000FF, 0x440000FF, 0xFFCCCCFF,
0xFF8888FF, 0xFF4444FF, };
mModes = new PorterDuff.Mode[] { PorterDuff.Mode.SRC_ATOP,//过滤器的方式
PorterDuff.Mode.MULTIPLY, };
mModeIndex = 0;
filter = new PorterDuffColorFilter(mColors [i], mModes[mModeIndex]);//用mColors [i]和porter-duff mode的颜色创建一个颜色过滤
mDrawable.setColorFilter(filter);
mDrawable.draw(canvas);
10.ColorMatrixTest
private void setContrast(ColorMatrix cm, float contrast) {
float scale = contrast + 1.f;
float translate = (-.5f * scale + .5f) * 255.f;
cm.set(new float[] { scale, 0, 0, 0, translate, 0, scale, 0, 0,
translate, 0, 0, scale, 0, translate, 0, 0, 0, 1, 0 });
}
ColorMatrix cm = new ColorMatrix();
mAngle += 2;
if (mAngle > 180) {
mAngle = 0;
}
float contrast = mAngle / 180.f;
setContrast(cm, contrast);
paint.setColorFilter(new ColorMatrixColorFilter(cm));//设置颜色过滤
canvas.drawBitmap(mBitmap, x + mBitmap.getWidth() + 10, y, paint);
invalidate();
11.Compass指南针：（没看）
12.CreateBitmap：
12.1 创建颜色数组（说实话没看懂）
private static int[] createColors() {
int[] colors = new int[STRIDE * HEIGHT];
for (int y = 0; y < HEIGHT; y++) {
for (int x = 0; x < WIDTH; x++) {
int r = x * 255 / (WIDTH - 1);
int g = y * 255 / (HEIGHT - 1);
int b = 255 - Math.min(r, g);
int a = Math.max(r, g);
colors[y * STRIDE + x] = (a << 24) | (r << 16) | (g << 8) | b;
}
}
return colors;
}
12.2
private static Bitmap codec(Bitmap src, Bitmap.CompressFormat format,
int quality) {
ByteArrayOutputStream os = new ByteArrayOutputStream();
src.compress(format, quality, os); //压缩
byte[] array = os.toByteArray();
return BitmapFactory.decodeByteArray(array, 0, array.length);
}
mJPEG[i] = codec(mBitmaps[i], Bitmap.CompressFormat.JPEG, 80);//用JPEG编码
13.DensityActivity
13.1
1: LinearLayout root =
new LinearLayout(
this);
//设置一个线性布局root
2:
root.setOrientation(LinearLayout.VERTICAL);
//方向垂直
3:
4:
LinearLayout layout =
new LinearLayout(
this);
//在root布局内，又建一个layout布局
5:
addBitmapDrawable(layout, R.drawable.logo120dpi,
true);
//以logo120dpi为View的背景，并把view加下布局
6:
7:
8:
addBitmapDrawable(layout, R.drawable.logo160dpi,
true);
9:
//addBitmapDrawable(layout, R.drawable.logo240dpi, true);
10:
addLabelToRoot(root,
"Prescaled bitmap in drawable");
//加入一个TextView到root
11:
addChildToRoot(root, layout);
12: setContentView(scrollWrap(root));
13:
14: }
15:
16:
1:
private void addLabelToRoot(LinearLayout root, String text) {
2: TextView label =
new TextView(
this);
3: label.setText(text);
4: root.addView(label,
new LinearLayout.LayoutParams(
5: LinearLayout.LayoutParams.FILL_PARENT,
6: LinearLayout.LayoutParams.WRAP_CONTENT));
7: }
8:
9:
private void addChildToRoot(LinearLayout root, LinearLayout layout) {
10: root.addView(layout,
new LinearLayout.LayoutParams(
11: LinearLayout.LayoutParams.FILL_PARENT,
12: LinearLayout.LayoutParams.WRAP_CONTENT));
13: }
14:
15:
16:
private Bitmap loadAndPrintDpi(
int id,
boolean scale) {
17: Bitmap bitmap;
18:
if (scale) {
19: bitmap = BitmapFactory.decodeResource(getResources(), id);
20: }
else {
21: BitmapFactory.Options opts =
new BitmapFactory.Options();
22: opts.inScaled =
false;
23: bitmap = BitmapFactory.decodeResource(getResources(), id, opts);
24: }
25:
return bitmap;
26: }
27:
28:
//将bitmap为作View的背景，并把view加下布局
1:
private void addBitmapDrawable(LinearLayout layout,
int resource,
2:
boolean scale) {
3: Bitmap bitmap;
4: bitmap = loadAndPrintDpi(resource, scale);
5:
6:
final View view =
new View(
this);
7: view.setOnClickListener(
new View.OnClickListener() {
//给当前veiw设置OnOnClickListener
8:
@Override
9:
public void onClick(View v) {
10:
//Toast.makeText(NewViewTest.this,"View onClick" , Toast.LENGTH_LONG).show();
11:
}
12: });
13: view.setOnTouchListener(
new View.OnTouchListener() {
//给当前view设置OnTouchListener
14:
@Override
15:
public boolean onTouch(View v, MotionEvent event) {
16: Toast.makeText(NewViewTest.
this,
"x="+event.getX()+
" y="+event.getY() , Toast.LENGTH_LONG).show();
17: v.setBackgroundColor(Color.BLUE);
18:
19:
return false;
20: }
21: });
22:
final BitmapDrawable d =
new BitmapDrawable(getResources(), bitmap);
23:
if (!scale)
24: d.setTargetDensity(getResources().getDisplayMetrics());
25: view.setBackgroundDrawable(d);
26:
27: view.setLayoutParams(
new LinearLayout.LayoutParams(d.getIntrinsicWidth(), d
28: .getIntrinsicHeight()));
29: layout.addView(view);
30: }
31:
private View scrollWrap(View view) {
32: ScrollView scroller =
new ScrollView(
this);
33: scroller.addView(view,
new ScrollView.LayoutParams(
34: ScrollView.LayoutParams.FILL_PARENT,
35: ScrollView.LayoutParams.FILL_PARENT));
36:
return scroller;
37: }
38:
39:
14. FingerPaint:手写板
14.1
1: MaskFilter mEmboss =
new EmbossMaskFilter(
new float[] { 1, 1, 1 }, 0.4f, 6, 3.5f);
//浮雕
2:
3:
MaskFilter mBlur =
new BlurMaskFilter(8, BlurMaskFilter.Blur.NORMAL);
//模糊
4:
14.2
//触摸事件
1:
public boolean onTouchEvent(MotionEvent event) {
2:
float x = event.getX();
3:
float y = event.getY();
4:
5:
switch (event.getAction()) {
6:
case MotionEvent.ACTION_DOWN:
7: touch_start(x, y);
8: invalidate();
9:
break;
10:
case MotionEvent.ACTION_MOVE:
11: touch_move(x, y);
12: invalidate();
13:
break;
14:
case MotionEvent.ACTION_UP:
15: touch_up();
16: invalidate();
17:
break;
18: }
19:
return true;
20: }
21:
14.3 画路径
1:
private float mX, mY;
2:
private static final float TOUCH_TOLERANCE = 4;
3:
4:
private void touch_start(
float x,
float y) {
5: mPath.reset();
6: mPath.moveTo(x, y);
//设置起始点
7:
mX = x;
8: mY = y;
9: }
10:
11:
private void touch_move(
float x,
float y) {
12:
float dx = Math.abs(x - mX);
13:
float dy = Math.abs(y - mY);
14:
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
15: mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
16: mX = x;
17: mY = y;
18: }
19: }
20:
21:
private void touch_up() {
22: mPath.lineTo(mX, mY);
23:
// commit the path to our offscreen
24:
mCanvas.drawPath(mPath, mPaint);
25:
// kill this so we don't double draw
26:
mPath.reset();
27: }
28:
29:
14.4此程序实现了接口implements
ColorPickerDialog.OnColorChangedListener
所以要实现方法
1:
public void colorChanged(
int color) {
2: mPaint.setColor(color);
3: Toast.makeText(FingerPaint.
this,
"colorChanged", Toast.LENGTH_LONG).show();
4: }
5:
在菜单选项中选择COLOR_MENU_ID时new ColorPickerDialog(this, this, mPaint.getColor()).show();//
1:
public boolean onOptionsItemSelected(MenuItem item) {
2: mPaint.setXfermode(
null);
3: mPaint.setAlpha(0xFF);
4:
5:
switch (item.getItemId()) {
6:
case COLOR_MENU_ID:
7:
new ColorPickerDialog(
this,
this, mPaint.getColor()).show();
//
8:
return true;
9:
case EMBOSS_MENU_ID:
10:
if (mPaint.getMaskFilter() != mEmboss) {
11: mPaint.setMaskFilter(mEmboss);
//设置为浮雕
12:
}
else {
13: mPaint.setMaskFilter(
null);
14: }
15:
return true;
16:
case BLUR_MENU_ID:
17:
if (mPaint.getMaskFilter() != mBlur) {
18: mPaint.setMaskFilter(mBlur);
19: }
else {
20: mPaint.setMaskFilter(
null);
21: }
22:
return true;
23:
case ERASE_MENU_ID:
24: mPaint.setXfermode(
new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
//设置Xfermode为擦除
25:
return true;
26:
case SRCATOP_MENU_ID:
27: mPaint.setXfermode(
new PorterDuffXfermode(PorterDuff.Mode.SRC_ATOP));
//此方法在VIEW上画完就清除
28:
mPaint.setAlpha(0x80);
29:
return true;
30: }
15. Layers:
15.1 没有第10，17行两个球边缘有锯齿
1:
private static final int LAYER_FLAGS = Canvas.
MATRIX_SAVE_FLAG
2:
| Canvas.
CLIP_SAVE_FLAG | Canvas.
HAS_ALPHA_LAYER_SAVE_FLAG
3:
| Canvas.
FULL_COLOR_LAYER_SAVE_FLAG | Canvas.
CLIP_TO_LAYER_SAVE_FLAG;
4:
@Override
5:
protected void onDraw(Canvas canvas) {
6: canvas.drawColor(Color.
WHITE);
7:
8: canvas.translate(10, 10);
9:
10: canvas.saveLayerAlpha(0, 0, 200, 200, 0x88,
LAYER_FLAGS);
11:
12:
mPaint.setColor(Color.
RED);
13: canvas.drawCircle(75, 75, 75,
mPaint);
14:
mPaint.setColor(Color.
BLUE);
15: canvas.drawCircle(125, 125, 75,
mPaint);
16:
17: canvas.restore();
18: }
16. MeasureText：
Paint的样式属性：
1:
mPaint =
new Paint();
2:
mPaint.setAntiAlias(
true);
3:
mPaint.setStrokeWidth(5);
4:
mPaint.setStrokeCap(Paint.Cap.
ROUND);
//在画点时，此句有效The shape of the point is controlled by the paint's Cap type
5:
mPaint.setTextSize(64);
6:
mPaint.setTypeface(Typeface.create(Typeface.
SERIF, Typeface.
ITALIC));
画字符的方法：
1:
private void showText(Canvas canvas, String text, Paint.Align align) {
2:
// mPaint.setTextAlign(align);
3:
4:
Rect bounds =
new Rect();
5:
float[] widths =
new float[text.length()];
6:
//获得字符串text中每个字符的像素宽存于widths中，返回字符串text的长度（有几个字符）
7:
int count =
mPaint.getTextWidths(text, 0, text.length(), widths);
8:
//获得字符串text整个像素宽
9:
float w =
mPaint.measureText(text, 0, text.length());
10:
//将字符串text所占矩形空间（最小，正好包起来）坐标存在bounds里
11:
mPaint.getTextBounds(text, 0, text.length(), bounds);
12:
13:
mPaint.setColor(0xFF88FF88);
14: canvas.drawRect(bounds,
mPaint);
15:
mPaint.setColor(Color.
BLACK);
16: canvas.drawText(text, 0, 0,
mPaint);
17:
//计算每个字符的刚好占的宽的点坐标
18:
float[] pts =
new float[2 + count * 2];
19:
float x = 0;
20:
float y = 0;
21: pts[0] = x;
22: pts[1] = y;
23:
for (
int i = 0; i < count; i++) {
24: x += widths[i];
25: pts[2 + i * 2] = x;
26: pts[2 + i * 2 + 1] = y;
27: }
28:
mPaint.setColor(Color.
RED);
29:
mPaint.setStrokeWidth(0);
30: canvas.drawLine(0, 0, w, 0,
mPaint);
31:
mPaint.setStrokeWidth(5);
32:
33: canvas.drawPoints(pts, 0, (count + 1) << 1,
mPaint);
//pts Array of points to draw [x0 y0 x1 y1 x2 y2 ...]
34:
}
onDraw方法:
1:
@Override
2:
protected void onDraw(Canvas canvas) {
3: canvas.drawColor(Color.
WHITE);
4:
5: canvas.translate(
mOriginX,
mOriginY);
//置换原点坐标
6:
7:
showText(canvas,
"Measure"
, Paint.Align.
LEFT
);
8:
canvas.translate(0, 80);
9:
showText(canvas,
"wiggy!"
, Paint.Align.
CENTER
);
10:
canvas.translate(0, 80);
11:
showText(canvas,
"Text"
, Paint.Align.
RIGHT
);
12:
}
17 .PathEffects：画动态路径，按中间键还能变换路径（没看）
18.PathFillTypes
path为两个圆：
1:
mPath =
new Path();
2:
mPath.addCircle(40, 40, 45, Path.Direction.
CCW);
3:
mPath.addCircle(80, 80, 45, Path.Direction.
CCW);
DrawPath方法：
1:
private void showPath(Canvas canvas,
int x,
int y, Path.FillType ft,
2: Paint paint) {
3: canvas.save();
//
4:
5:
canvas.translate(x, y);
6: canvas.clipRect(0, 0, 120, 120);
7: canvas.drawColor(Color.
WHITE);
8:
mPath.setFillType(ft);
//设置填充方式
9:
canvas.drawPath(
mPath, paint);
10:
11: canvas.restore();
12: }
onDraw方法：
1:
@Override
2:
protected void onDraw(Canvas canvas) {
3: Paint paint =
mPaint;
4:
5: canvas.drawColor(0xFFCCCCCC);
6:
7: canvas.translate(20, 20);
8:
9: paint.setAntiAlias(
true);
10:
//用四种填充方式画4次path
11:
showPath(canvas, 0, 0, Path.FillType.
WINDING, paint);
12: showPath(canvas, 160, 0, Path.FillType.
EVEN_ODD, paint);
13: showPath(canvas, 0, 160, Path.FillType.
INVERSE_WINDING, paint);
14: showPath(canvas, 160, 160, Path.FillType.
INVERSE_EVEN_ODD, paint);
15: }
19.Patterns: 触摸拖动时，上面的一层可以动
上层的图形（小图）
1:
private static
Bitmap makeBitmap2() {
2:
Bitmap bm = Bitmap.createBitmap(64, 64, Bitmap.Config.
ARGB_8888
);
3:
Canvas c =
new
Canvas(bm);
4:
Paint p =
new
Paint(Paint.
ANTI_ALIAS_FLAG
);
5:
p.setColor(Color.
GREEN
);
6:
p.setAlpha(0xCC);
// 0XFF为完全透明，0X00为完全不透明
7:
c.drawCircle(32, 32, 27, p);
8:
return
bm;
9:
}
View的构造方法中创建mShader2 ：
1:
public SimlpeView(Context context) {
2:
super(context);
3: setFocusable(
true);
4: setFocusableInTouchMode(
true);
5:
6:
mFastDF =
new PaintFlagsDrawFilter(Paint.
FILTER_BITMAP_FLAG
7:
| Paint.
DITHER_FLAG, 0);
// 不懂是什么意思？
8:
mShader2 =
new BitmapShader(makeBitmap2(), Shader.TileMode.
REPEAT,
9: Shader.TileMode.
REPEAT);
// 用张小图，拼成一个地转多块的大图
10:
11:
Matrix m =
new Matrix();
12: m.setRotate(30);
13:
mShader2.setLocalMatrix(m);
// 图mShader2设置30度的旋转
14:
15:
mPaint =
new Paint(Paint.
FILTER_BITMAP_FLAG);
16: }
onDraw方法：
1:
@Override
2:
protected void onDraw(Canvas canvas) {
3:
super.onDraw(canvas);
4: canvas.setDrawFilter(
mDF);
5: canvas.translate(
mTouchCurrX -
mTouchStartX,
mTouchCurrY -
mTouchStartY);
// 用触摸的位移作为原点，让图动起来
6:
7:
mPaint.setShader(
mShader2);
//把整个图形作为样式
8:
canvas.drawPaint(
mPaint);
//重要
9:
}
onTouchEvent方法（控制原点坐标为触摸相对位移）：
1:
@Override
2:
public boolean
onTouchEvent(MotionEvent event) {
3:
float
x = event.getX();
4:
float
y = event.getY();
5:
switch
(event.getAction()) {
6:
case
MotionEvent.
ACTION_DOWN
:
7:
mTouchCurrX
=
mTouchStartX
= x;
8:
mTouchCurrY
=
mTouchStartY
= y;
9:
mDF
=
mFastDF
;
10:
invalidate();
11:
break
;
12:
case
MotionEvent.
ACTION_MOVE
:
13:
mTouchCurrX
= x;
14:
mTouchCurrY
= y;
15:
invalidate();
16:
break
;
17:
case
MotionEvent.
ACTION_UP
:
18:
mDF
=
null
;
19:
invalidate();
20:
break
;
21:
default
:
22:
break
;
23:
}
24:
return true
;
// super.onTouchEvent(event);此处一定是true才能触摸起作用
25:
}
20.Pictures：针对Picture对象的画法
新建Picture对象，从beginRecording开始记录画图命令，到endRecording，其间画的图全画在Picture里了（第2，3行）：
第5行表明可以从一个Picture对象，得到一个Drawable
1:
mPicture
=
new
Picture();
//新建一个Picture对象
2:
drawSomething(
mPicture
.beginRecording(200, 100));
//在mPicture上作画。记录所有draw命令,beginRecording为开始记录
3:
mPicture
.endRecording();
//结束记录
4:
5:
mDrawable
=
new
PictureDrawable(
mPicture
);
//从Picture得到一个Drawable
drawSomething（）方法：在Picture上画一个圆和字符串
1:
static void drawSomething(Canvas canvas) {
2: Paint p =
new Paint(Paint.
ANTI_ALIAS_FLAG);
3:
4: p.setColor(0x88FF0000);
5: canvas.drawCircle(50, 50, 40, p);
6:
7: p.setColor(Color.
GREEN);
8: p.setTextSize(30);
9: canvas.drawText(
"Pictures", 60, 60, p);
10: }
Picture的几法画法：
1:
@Override
2:
protected void onDraw(Canvas canvas) {
3: canvas.drawColor(Color.
WHITE);
4:
5: canvas.drawPicture(
mPicture);
//画Picture
6:
7:
canvas.drawPicture(
mPicture,
new RectF(0, 100, getWidth(), 200));
//stretched 拉申在这矩形里
8:
9:
mDrawable.setBounds(0, 200, getWidth(), 300);
10:
mDrawable.draw(canvas);
11:
12: ByteArrayOutputStream os =
new ByteArrayOutputStream();
13:
mPicture.writeToStream(os);
//Picture可以写入流中
14:
InputStream is =
new ByteArrayInputStream(os.toByteArray());
15: canvas.translate(0, 300);
16: canvas.drawPicture(Picture.createFromStream(is));
//从流中创建Picture对象
17:
}
21. PolyToPoly:
先画出第一个图：
paint的属性：
1:
mPaint.setStrokeWidth(4);
2:
mPaint.setTextSize(40);
3:
mPaint.setTextAlign(Paint.Align.
CENTER);
4:
5:
mFontMetrics =
mPaint.getFontMetrics();
//
画图方法：
1:
private Paint
mPaint =
new Paint(Paint.
ANTI_ALIAS_FLAG);
2:
private FontMetrics
mFontMetrics;
3:
4:
private void doDraw(Canvas canvas,
float src[],
float dst[]) {
5: canvas.save();
6:
7:
mPaint.setColor(Color.
GRAY);
8:
mPaint.setStyle(Paint.Style.
STROKE);
9: canvas.drawRect(0, 0, 64, 64,
mPaint);
10: canvas.drawLine(0, 0, 64, 64,
mPaint);
11: canvas.drawLine(0, 64, 64, 0,
mPaint);
12:
13:
mPaint.setColor(Color.
RED);
14:
mPaint.setStyle(Paint.Style.
FILL);
15:
float x = 64 / 2;
16:
float y = 64 / 2-(
mFontMetrics.
ascent+
mFontMetrics.
descent)/2;
17: canvas.drawText(src.
length / 2 +
"", x, y,
mPaint);
18: canvas.restore();
19: }
注意：如果没有mFontMetrics = mPaint.getFontMetrics();//和第16句的话，画出来的图是
在上面代码的基础上加入mMatrix.setPolyToPoly
1:
private void doDraw(Canvas canvas,
float src[],
float dst[]) {
2: canvas.save();
3:
4:
mMatrix.setPolyToPoly(src, 0, dst, 0, src.
length >> 1);
//
5:
canvas.concat(
mMatrix);
//
6:
7:
mPaint.setColor(Color.
GRAY);
8:
mPaint.setStyle(Paint.Style.
STROKE);
9: canvas.drawRect(0, 0, 64, 64,
mPaint);
10: canvas.drawLine(0, 0, 64, 64,
mPaint);
11: canvas.drawLine(0, 64, 64, 0,
mPaint);
12:
13:
mPaint.setColor(Color.
RED);
14:
mPaint.setStyle(Paint.Style.
FILL);
15:
float x = 64 / 2;
16:
float y = 64 / 2 - (
mFontMetrics.
ascent +
mFontMetrics.
descent) / 2;
17: canvas.drawText(src.
length / 2 +
"", x, y,
mPaint);
18: canvas.restore();
19: }
onDraw方法：
1:
@Override
2:
protected void onDraw(Canvas canvas) {
3:
super.onDraw(canvas);
4: canvas.drawColor(Color.
WHITE);
5: doDraw(canvas,
new float[] { 0, 0,64,32 },
new float[] { 32, 32,160,192 });
6: }
现在画出的图为：
可以看出在new float[] { 0, 0,64,32 }, new float[] { 32, 32,160,192 }两个数组中的坐标为，（0，0）点置换到（32，32）点，（64，32）点（也就是1图的右边中间点）置换到（160，192）也就是屏幕中间X坐标
doDraw(canvas, new float[] { 0, 0,64,32 }, new float[] { 32, 32,160,192 });
22. Regions
画两个空心矩形方法：加上inset线条会很细，不加是这样的
加了是
1:
private static void drawCentered(Canvas c, Rect r, Paint p) {
2:
float inset = p.getStrokeWidth() * 0.5f;
3:
if (inset == 0) {
// catch hairlines
4:
inset = 0.5f;
5: }
6: c.drawRect(r.
left + inset, r.
top + inset, r.
right - inset, r.
bottom
7:
- inset, p);
8: }
上面4个图的核心画法：
1:
private void drawRgn(Canvas canvas,
int color, String str, Region.Op op) {
2:
if (str !=
null) {
3:
mPaint.setColor(Color.
BLACK);
4: canvas.drawText(str, 80, 24,
mPaint);
5: }
6:
7: Region rgn =
new Region();
8: rgn.set(
mRect1);
9: rgn.op(
mRect2, op);
10:
11:
mPaint.setColor(color);
12: RegionIterator iter =
new RegionIterator(rgn);
13: Rect
r =
new
Rect();
14:
15:
canvas.translate(0, 30);
16:
mPaint
.setColor(color);
17:
while
(iter.next(
r)) {
18:
canvas.drawRect(r,
mPaint
);
19:
}
20:
drawOriginalRects(canvas, 0x80);
21:
}
onDraw方法：
1:
@Override
2:
protected void onDraw(Canvas canvas) {
3: canvas.drawColor(Color.
GRAY);
4:
5: canvas.save();
6: canvas.translate(80, 5);
7: drawOriginalRects(canvas, 0xFF);
8: canvas.restore();
9:
10:
mPaint.setStyle(Paint.Style.
FILL);
11:
12: canvas.save();
13: canvas.translate(0, 140);
14: drawRgn(canvas, Color.
RED,
"Union", Region.Op.
UNION);
15: canvas.restore();
16:
17: canvas.save();
18: canvas.translate(0, 280);
19: drawRgn(canvas, Color.
BLUE,
"Xor", Region.Op.
XOR);
20: canvas.restore();
21:
22: canvas.save();
23: canvas.translate(160, 140);
24: drawRgn(canvas, Color.
GREEN,
"Difference", Region.Op.
DIFFERENCE);
25: canvas.restore();
26:
27: canvas.save();
28: canvas.translate(160, 280);
29: drawRgn(canvas, Color.
WHITE,
"Intersect", Region.Op.
INTERSECT);
30: canvas.restore();
31: }
