本文介绍了通过手指，Android的画在画布的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我需要建立一个项目，用手指在画布上绘画，
I need to build a project for drawing on canvas by fingers,
让我的手指的触摸事件和运动事件，并由此得出。
to get the touch event and motion event of my finger, and thence draw.
任何一个可以指点我怎么去启动项目，
Any one can advice me how to get start in project,
什么是做这样的事情最好的成分？
and what is best component to do thing like this?
推荐答案
首先，经过Fingerpaint演示SDK的样本。
Start By going through the Fingerpaint demo in the sdk sample.
另外一个示例：
public class MainActivity extends Activity {
DrawingView dv ;
private Paint mPaint;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
dv = new DrawingView(this);
setContentView(dv);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(Color.GREEN);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(12);
}
public class DrawingView extends View {
public int width;
public int height;
private Bitmap mBitmap;
private Canvas mCanvas;
private Path mPath;
private Paint mBitmapPaint;
Context context;
private Paint circlePaint;
private Path circlePath;
public DrawingView(Context c) {
super(c);
context=c;
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
circlePaint = new Paint();
circlePath = new Path();
circlePaint.setAntiAlias(true);
circlePaint.setColor(Color.BLUE);
circlePaint.setStyle(Paint.Style.STROKE);
circlePaint.setStrokeJoin(Paint.Join.MITER);
circlePaint.setStrokeWidth(4f);
}
@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) {
super.onDraw(canvas);
canvas.drawBitmap( mBitmap, 0, 0, mBitmapPaint);
canvas.drawPath( mPath, mPaint);
canvas.drawPath( circlePath, circlePaint);
}
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;
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) {
mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
mX = x;
mY = y;
circlePath.reset();
circlePath.addCircle(mX, mY, 30, Path.Direction.CW);
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
circlePath.reset();
// commit the path to our offscreen
mCanvas.drawPath(mPath, mPaint);
// kill this so we don't double draw
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;
}
}
}
快照
说明：
您正在创建一个视图类，然后扩展视图。你覆盖的OnDraw（）。你加在哪里手指触摸和移动路径。重写这一宗旨的onTouch（）。在你的OnDraw（）绘制使用您所选择的油漆的路径。你应该调用无效（）刷新视图。
You are creating a view class then extends View. You override the onDraw(). You add the path of where finger touches and moves. You override the onTouch() of this purpose. In your onDraw() you draw the paths using the paint of your choice. You should call invalidate() to refresh the view.
要选择选项，您可以点击菜单，选择选项。
To choose options you can click menu and choose the options.
的下面，可作为参考。您可以根据自己的需要修改如下：
The below can be used as a reference. You can modify the below according to your needs.
public class FingerPaintActivity extends Activity
implements ColorPickerDialog.OnColorChangedListener {
MyView mv;
AlertDialog dialog;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mv= new MyView(this);
mv.setDrawingCacheEnabled(true);
mv.setBackgroundResource(R.drawable.afor);//set the back ground if you wish to
setContentView(mv);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(0xFFFF0000);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(20);
mEmboss = new EmbossMaskFilter(new float[] { 1, 1, 1 },
0.4f, 6, 3.5f);
mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.NORMAL);
}
private Paint mPaint;
private MaskFilter mEmboss;
private MaskFilter mBlur;
public void colorChanged(int color) {
mPaint.setColor(color);
}
public class MyView extends View {
private static final float MINP = 0.25f;
private static final float MAXP = 0.75f;
private Bitmap mBitmap;
private Canvas mCanvas;
private Path mPath;
private Paint mBitmapPaint;
Context context;
public MyView(Context c) {
super(c);
context=c;
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
}
@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) {
super.onDraw(canvas);
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
canvas.drawPath(mPath, mPaint);
}
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;
private void touch_start(float x, float y) {
//showDialog();
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) {
mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
mX = x;
mY = y;
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
// commit the path to our offscreen
mCanvas.drawPath(mPath, mPaint);
// kill this so we don't double draw
mPath.reset();
mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SCREEN));
//mPaint.setMaskFilter(null);
}
@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 + 1;
private static final int BLUR_MENU_ID = Menu.FIRST + 2;
private static final int ERASE_MENU_ID = Menu.FIRST + 3;
private static final int SRCATOP_MENU_ID = Menu.FIRST + 4;
private static final int Save = Menu.FIRST + 5;
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
menu.add(0, COLOR_MENU_ID, 0, "Color").setShortcut('3', 'c');
menu.add(0, EMBOSS_MENU_ID, 0, "Emboss").setShortcut('4', 's');
menu.add(0, BLUR_MENU_ID, 0, "Blur").setShortcut('5', 'z');
menu.add(0, ERASE_MENU_ID, 0, "Erase").setShortcut('5', 'z');
menu.add(0, SRCATOP_MENU_ID, 0, "SrcATop").setShortcut('5', 'z');
menu.add(0, Save, 0, "Save").setShortcut('5', 'z');
return true;
}
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
super.onPrepareOptionsMenu(menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
mPaint.setXfermode(null);
mPaint.setAlpha(0xFF);
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:
mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
mPaint.setAlpha(0x80);
return true;
case SRCATOP_MENU_ID:
mPaint.setXfermode(new PorterDuffXfermode(
PorterDuff.Mode.SRC_ATOP));
mPaint.setAlpha(0x80);
return true;
case Save:
AlertDialog.Builder editalert = new AlertDialog.Builder(FingerPaintActivity.this);
editalert.setTitle("Please Enter the name with which you want to Save");
final EditText input = new EditText(FingerPaintActivity.this);
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.FILL_PARENT,
LinearLayout.LayoutParams.FILL_PARENT);
input.setLayoutParams(lp);
editalert.setView(input);
editalert.setPositiveButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
String name= input.getText().toString();
Bitmap bitmap = mv.getDrawingCache();
String path = Environment.getExternalStorageDirectory().getAbsolutePath();
File file = new File("/sdcard/"+name+".png");
try
{
if(!file.exists())
{
file.createNewFile();
}
FileOutputStream ostream = new FileOutputStream(file);
bitmap.compress(CompressFormat.PNG, 10, ostream);
ostream.close();
mv.invalidate();
}
catch (Exception e)
{
e.printStackTrace();
}finally
{
mv.setDrawingCacheEnabled(false);
}
}
});
editalert.show();
return true;
}
return super.onOptionsItemSelected(item);
}
}
拾色器
public class ColorPickerDialog extends Dialog {
public interface OnColorChangedListener {
void colorChanged(int color);
}
private OnColorChangedListener mListener;
private int mInitialColor;
private static class ColorPickerView extends View {
private Paint mPaint;
private Paint mCenterPaint;
private final int[] mColors;
private OnColorChangedListener mListener;
ColorPickerView(Context c, OnColorChangedListener l, int color) {
super(c);
mListener = l;
mColors = new int[] {
0xFFFF0000, 0xFFFF00FF, 0xFF0000FF, 0xFF00FFFF, 0xFF00FF00,
0xFFFFFF00, 0xFFFF0000
};
Shader s = new SweepGradient(0, 0, mColors, null);
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setShader(s);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeWidth(32);
mCenterPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mCenterPaint.setColor(color);
mCenterPaint.setStrokeWidth(5);
}
private boolean mTrackingCenter;
private boolean mHighlightCenter;
@Override
protected void onDraw(Canvas canvas) {
float r = CENTER_X - mPaint.getStrokeWidth()*0.5f;
canvas.translate(CENTER_X, CENTER_X);
canvas.drawOval(new RectF(-r, -r, r, r), mPaint);
canvas.drawCircle(0, 0, CENTER_RADIUS, mCenterPaint);
if (mTrackingCenter) {
int c = mCenterPaint.getColor();
mCenterPaint.setStyle(Paint.Style.STROKE);
if (mHighlightCenter) {
mCenterPaint.setAlpha(0xFF);
} else {
mCenterPaint.setAlpha(0x80);
}
canvas.drawCircle(0, 0,
CENTER_RADIUS + mCenterPaint.getStrokeWidth(),
mCenterPaint);
mCenterPaint.setStyle(Paint.Style.FILL);
mCenterPaint.setColor(c);
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(CENTER_X*2, CENTER_Y*2);
}
private static final int CENTER_X = 100;
private static final int CENTER_Y = 100;
private static final int CENTER_RADIUS = 32;
private int floatToByte(float x) {
int n = java.lang.Math.round(x);
return n;
}
private int pinToByte(int n) {
if (n < 0) {
n = 0;
} else if (n > 255) {
n = 255;
}
return n;
}
private int ave(int s, int d, float p) {
return s + java.lang.Math.round(p * (d - s));
}
private int interpColor(int colors[], float unit) {
if (unit <= 0) {
return colors[0];
}
if (unit >= 1) {
return colors[colors.length - 1];
}
float p = unit * (colors.length - 1);
int i = (int)p;
p -= i;
// now p is just the fractional part [0...1) and i is the index
int c0 = colors[i];
int c1 = colors[i+1];
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 rotateColor(int color, float rad) {
float deg = rad * 180 / 3.1415927f;
int r = Color.red(color);
int g = Color.green(color);
int b = Color.blue(color);
ColorMatrix cm = new ColorMatrix();
ColorMatrix tmp = new ColorMatrix();
cm.setRGB2YUV();
tmp.setRotate(0, deg);
cm.postConcat(tmp);
tmp.setYUV2RGB();
cm.postConcat(tmp);
final float[] a = cm.getArray();
int ir = floatToByte(a[0] * r + a[1] * g + a[2] * b);
int ig = floatToByte(a[5] * r + a[6] * g + a[7] * b);
int ib = floatToByte(a[10] * r + a[11] * g + a[12] * b);
return Color.argb(Color.alpha(color), pinToByte(ir),
pinToByte(ig), pinToByte(ib));
}
private static final float PI = 3.1415926f;
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX() - CENTER_X;
float y = event.getY() - CENTER_Y;
boolean inCenter = java.lang.Math.sqrt(x*x + y*y) <= CENTER_RADIUS;
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mTrackingCenter = inCenter;
if (inCenter) {
mHighlightCenter = true;
invalidate();
break;
}
case MotionEvent.ACTION_MOVE:
if (mTrackingCenter) {
if (mHighlightCenter != inCenter) {
mHighlightCenter = inCenter;
invalidate();
}
} else {
float angle = (float)java.lang.Math.atan2(y, x);
// need to turn angle [-PI ... PI] into unit [0....1]
float unit = angle/(2*PI);
if (unit < 0) {
unit += 1;
}
mCenterPaint.setColor(interpColor(mColors, unit));
invalidate();
}
break;
case MotionEvent.ACTION_UP:
if (mTrackingCenter) {
if (inCenter) {
mListener.colorChanged(mCenterPaint.getColor());
}
mTrackingCenter = false; // so we draw w/o halo
invalidate();
}
break;
}
return true;
}
}
public ColorPickerDialog(Context context,
OnColorChangedListener listener,
int initialColor) {
super(context);
mListener = listener;
mInitialColor = initialColor;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
OnColorChangedListener l = new OnColorChangedListener() {
public void colorChanged(int color) {
mListener.colorChanged(color);
dismiss();
}
};
setContentView(new ColorPickerView(getContext(), l, mInitialColor));
setTitle("Pick a Color");
}
}
这篇关于通过手指，Android的画在画布的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！