/*
* 這個demon示範了如何在畫闆上自由繪制圖形，可以選擇繪制的顔色，可以設定線條的浮雕和毛邊效果
* 可以擦除，還實作了一種圖像的整合模式。
*/
public class MainActivity extends Activity implements OnColorChangedListener {
private Paint mPaint;
// 設定筆刷的浮雕效果
private MaskFilter mEmboss;
// 設定筆刷的毛邊效果
private MaskFilter mBlur;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new MyView(this));
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor();
mPaint.setStyle(Paint.Style.STROKE);
// 設定結合處的樣式為圓角
mPaint.setStrokeJoin(Paint.Join.ROUND);
// 設定畫筆的筆觸風格為圓形
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth();
mEmboss = new EmbossMaskFilter(new float[] { , , }, f, , f);
mBlur = new BlurMaskFilter(, BlurMaskFilter.Blur.NORMAL);
}
private class MyView extends View {
private Path mPath;
private Paint mBitmapPaint;
private Bitmap mBitmap;
private Canvas mCanvas;
public MyView(Context context) {
super(context);
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
}
// 當視圖大小發生變化時重置畫布
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawColor();
canvas.drawBitmap(mBitmap, , , mBitmapPaint);
canvas.drawPath(mPath, mPaint);
}
float mx, my;
// 定義移動的幅度
private static final float TOUCH_TOLERANCE = ;
private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mx = x;
my = y;
}
private void touch_move(float x, float y) {
float dx = Math.abs(x - mx);
float dy = Math.abs(y - my);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
/*
* 該方法用于繪制一條貝塞爾曲線（圓滑的弧線）前兩個參數表示節點（控制點，用于控制
* 曲線的彎曲和弧度），後兩個參數表示結束點的坐标，線段的開始點則為Path最近
* moveto的地方。這裡将控制點與新坐标的中點作為結束點，下次再次調用該方法時
* 将新的坐标點作為控制點，控制點就位于起始點和結束點大約中央的位置。
*/
mPath.quadTo(mx, my, (mx + x) / , (my + y) / );
mx = x;
my = y;
}
}
private void touch_up() {
mPath.lineTo(mx, my);
// 繪制路徑
mCanvas.drawPath(mPath, mPaint);
// 重置路徑
mPath.reset();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touch_start(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
touch_move(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
touch_up();
invalidate();
break;
}
return true;
}
}
private static final int COLOR_MENU_ID = Menu.FIRST;
private static final int EMBOSS_MENU_ID = Menu.FIRST + ;
private static final int BLUR_MENU_ID = Menu.FIRST + ;
private static final int ERASE_MENU_ID = Menu.FIRST + ;
private static final int SRCATOP_MENU_ID = Menu.FIRST + ;
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
menu.add(, COLOR_MENU_ID, , "Color");
menu.add(, EMBOSS_MENU_ID, , "Emboss");
menu.add(, BLUR_MENU_ID, , "Blur");
menu.add(, ERASE_MENU_ID, , "Erase");
menu.add(, SRCATOP_MENU_ID, , "SrcTop");
return true;
}
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
super.onPrepareOptionsMenu(menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
mPaint.setXfermode(null);
mPaint.setAlpha();
switch (item.getItemId()) {
case COLOR_MENU_ID:
new ColorPickerDialog(this, this, mPaint.getColor()).show();
return true;
case EMBOSS_MENU_ID:
if(mPaint.getMaskFilter()!=mEmboss){
mPaint.setMaskFilter(mEmboss);
}else{
mPaint.setMaskFilter(null);
}
return true;
case BLUR_MENU_ID:
if(mPaint.getMaskFilter()!=mBlur){
mPaint.setMaskFilter(mBlur);
}else{
mPaint.setMaskFilter(null);
}
return true;
case ERASE_MENU_ID:
//設定整合模式
mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
return true;
case SRCATOP_MENU_ID:
//該模式下隻顯示原圖和新繪制的圖形與原圖相交的部分
mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_ATOP));
mPaint.setAlpha();
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void colorChanged(int color) {
mPaint.setColor(color);
}
}
ColorPickerDialog
/*
* 定義一個顔色選擇器
*/
public class ColorPickerDialog extends Dialog {
// 定義一個接口用于監聽顔色的變化
public interface OnColorChangedListener {
void colorChanged(int color);
}
private OnColorChangedListener mListener;
// 定義初始顔色
private int mInitialColor;
// 定義對話框的界面視圖
private class ColorPickerView extends View {
// 定義畫外圓的畫筆
private Paint mPaint;
// 定義内圓的畫筆
private Paint mCenterPaint;
private int[] mColors;
private OnColorChangedListener mColorChangedListener;
public ColorPickerView(Context context, OnColorChangedListener l,
int color) {
super(context);
// 在構造方法中初始化定義的各個類
mColorChangedListener = l;
mColors = new int[] { , , ,
, , , };
// 以0，0為圓心進行掃描漸變，後面我們會将畫布移至圓心
Shader s = new SweepGradient(, , mColors, null);
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setShader(s);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeWidth();
mCenterPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mCenterPaint.setColor(color);
mCenterPaint.setStrokeWidth();
}
// 用于判定是否在内圓的内部移動
private boolean mTrackingCenter;
// 用于判定是否高亮顯示内圓的描邊
private boolean mHeightLightCenter;
private static final int CENTER_X = ;
private static final int CENTER_Y = ;
private static final int CENTER_RADIUS = ;
@Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.BLACK);
float r = CENTER_X - mPaint.getStrokeWidth() * f;
// 移動畫布至圓心
canvas.translate(CENTER_X, CENTER_Y);
// 繪制一個寬度為32的圓環
canvas.drawCircle(, , r, mPaint);
// 以初始的顔色繪制内部小圓
canvas.drawCircle(, , CENTER_RADIUS, mCenterPaint);
// 如果按下時與螢幕的接觸點位于小圓的内部，則以相同的顔色為小圓描邊
if (mTrackingCenter) {
//int c=mCenterPaint.getColor();
mCenterPaint.setStyle(Paint.Style.STROKE);
if (mHeightLightCenter) {
// 如果高亮顯示則設定畫筆的透明度為完全不透明
mCenterPaint.setAlpha();
} else {
// 如果不需要高亮顯示則降低透明度
mCenterPaint.setAlpha();
}
// 繪制描邊
canvas.drawCircle(, , mCenterPaint.getStrokeWidth()
+ CENTER_RADIUS, mCenterPaint);
// 将畫筆的風格設定回填充模式
mCenterPaint.setStyle(Paint.Style.FILL);
//mCenterPaint.setColor(c);
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(CENTER_X * , CENTER_Y * );
}
private static final float PI = f;
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX() -CENTER_X;
float y = event.getY() -CENTER_Y;
// 判斷觸點是否在内圓的内部（通過觸點與圓間的距離不大于于内圓半徑）
boolean inCenter = Math.sqrt(x * x + y * y) <= CENTER_RADIUS;
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mTrackingCenter = inCenter;
if (inCenter) {
mHeightLightCenter = true;
invalidate();
break;
}
case MotionEvent.ACTION_MOVE:
if (mTrackingCenter) {
if (mHeightLightCenter != inCenter) {
mHeightLightCenter = inCenter;
invalidate();
}
} else {
System.out.println("按下即使不動也會進入到這個方法！在這裡設定畫筆的顔色");
// 計算接觸點至圓心的連線與X方向夾角的弧度
float angle = (float) Math.atan2(y, x);
// angle的取值範圍為【-PI—，PI】，我們現在需要将該值轉化為0-1的數
float unit = angle / ( * PI);
if (unit < ) {
// 将-1/2——0部分的值轉化為1/2——1的值
unit += ;
}
mCenterPaint.setColor(interpColor(mColors, unit));
invalidate();
}
break;
case MotionEvent.ACTION_UP:
if (mTrackingCenter) {
if (inCenter) {
//如果按下和松開時觸點都位于小圓内部，則調用接口的方法，為接口的參數指派
mColorChangedListener.colorChanged(mCenterPaint.getColor());
}
mTrackingCenter=false;
invalidate();
}
break;
}
return true;
}
// 根據觸點的位置，計算目前位置的顔色值，根據內插補點計算法
private int interpColor(int[] colors, float unit) {
// 確定取得顔色的值
if (unit < ) {
return colors[];
}
if (unit >= ) {
return colors[colors.length - ];
}
// 計算觸點映射到顔色數組中的相對位置
float p = (colors.length - ) * unit;
// 取出相對位置的整數部分
int i = (int) p;
// 取出相對位置的小數部分
p -= i;
// 計算顔色的值，利用內插補點計算法
int c0 = colors[i];
int c1 = colors[i + ];
int a = ave(Color.alpha(c0), Color.alpha(c1), p);
int r = ave(Color.red(c0), Color.red(c1), p);
int g = ave(Color.green(c0), Color.green(c1), p);
int b = ave(Color.blue(c0), Color.blue(c1), p);
return Color.argb(a, r, g, b);
}
private int ave(int s, int d, float p) {
return s + Math.round((d - s) * p);
}
}
public ColorPickerDialog(Context context,OnColorChangedListener listener,int initialColor) {
super(context);
mListener=listener;
mInitialColor=initialColor;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//實作接口
OnColorChangedListener l=new OnColorChangedListener() {
@Override
public void colorChanged(int color) {
//調用引用并建立該對話框的類中實作的該接口的方法
mListener.colorChanged(color);
dismiss();
}
};
setContentView(new ColorPickerView(getContext(), l, mInitialColor));
setTitle("Pick a Color");
}
}
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