I read the article on http://www.curious-creature.org/2013/12/21/android-recipe-4-path-tracing/
Trying to draw arrows with Path which mentioned in the article, but with the following code, I got the half arrow, I already read articles about how to draw arrows on android. This question is more about "what's wrong with the following code." Thanks in advance.
package com.example.linepractice;
import android.os.Bundle;
import android.app.Activity;
import android.view.LayoutInflater;
import android.widget.LinearLayout;
import android.widget.LinearLayout.LayoutParams;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
PracticeLineView pl = new PracticeLineView(this);
LayoutInflater mInflater = LayoutInflater.from(this);
LinearLayout mainView = (LinearLayout) mInflater.inflate(R.layout.activity_main, null);
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.setMargins(120, 120, 120, 120);
pl.setLayoutParams(params);
mainView.addView(pl);
setContentView(mainView);
}
}
package com.example.linepractice;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.view.View;
public class PracticeLineView extends View {
private Paint mPaint;
public PracticeLineView(Context context) {
super(context);
mPaint = new Paint();
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.translate(getPaddingLeft(), getPaddingTop() - getPaddingBottom());
canvas.drawPath(makeArrow(140,140), mPaint);
}
private static Path makeArrow(float length, float height) {
Path p = new Path();
p.moveTo(-2.0f, -height / 2.0f);
p.lineTo(length, 0.0f);
p.lineTo(-2.0f, height / 2.0f);
p.lineTo(-2.0f, -height / 2.0f);
p.close();
return p;
}
}
pic:
private static Path makeArrow(float length, float height) {
Path p = new Path();
p.moveTo(-2.0f, 0.0f);
p.lineTo(length, height / 2.0f);
p.lineTo(-2.0f, height);
p.lineTo(-2.0f, 0.0f);
p.close();
return p;
}
Related
I have an imageView and I draw the diagram in imageView according to the coordinate array. Every diagram has an onclick event.
Activity.java
package com.example.floorexhibitiontest;
import com.floor.DrawView;
import android.app.Activity;
import android.os.Bundle;
import android.widget.LinearLayout;
public class HallActivity extends Activity {#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.hall);
}
float[][][] points = new float[][][] {
{
{213,264},
{247,232},
{345,338},
{310,371}
},
{
{171,305},
{205,272},
{302,373},
{267,406}
},
{
{571,320},
{606,320},
{606,428},
{571,428}
}
};
LinearLayout layout = (LinearLayout)findViewById(R.id.root);
final DrawView draw = new DrawView(this,points);
layout.addView(draw);
}
DrawView.java
package com.floor;
import com.example.floorexhibitiontest.R;
import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Path;
import android.graphics.Paint.Style;
import android.graphics.Shader.TileMode;
import android.graphics.Shader;
import android.util.DisplayMetrics;
import android.view.View;
public class DrawView extends View{
private float[][][] points = null;
DisplayMetrics metric = new DisplayMetrics();
public DrawView(Context context,float[][][] p) {
super(context);
metric = context.getApplicationContext().getResources().getDisplayMetrics();
points = p;
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
float density=metric.density;
for(int i = 0; i < points.length; i++){
Paint p = new Paint();
p.setAntiAlias(true);
p.setColor(Color.BLUE);
Path path=new Path();
path.moveTo(points[i][0][0] / density, points[i][0][1] / density);
path.lineTo(points[i][1][0] / density, points[i][1][1] / density);
path.lineTo(points[i][2][0] / density, points[i][2][1] / density);
path.lineTo(points[i][3][0] / density, points[i][3][1] / density);
path.close();
p.setStyle(Style.STROKE);
canvas.drawPath(path, p);
}
}
}
At present effect：
How to let each rectangular drawed produce their own onclick event?
There is an ImageView in Layout file. My purpose is to put the graphics paint on the ImageView. But the result is ImageView can display. The painted graphics can not display. If I hide
ImageView, the image can display.
Ask everyone’s help. Thanks in advice.
Try smth like this:
public boolean onTouch(View v, MotionEvent event) {
if((event.getX(0)>=x_coord) &&
(event.getY(0)>=y_coord) &&
( event.getX(0)<=x_coord + your_rectangle_width) &&
(event.getY(0)<=y_coord + your_rectangle_heigth))
{
//rectangle selected
}
return true;
}
Or use in onTouch() your actual coordinates from points[] array
I want to draw a stack which should raise from the bottom. For example the stack height is 400, from the height 10 it should grow till it reaches 400.
I want to do this using paint and canvas.
I don't want to do it with image view/bitmap and scale animation.
Is it possible to do this with canvas and paint? if so how to achieve it?
Thanks in advance.
You could try using something like this (have not tested myself):
Paint paint = new Paint();
paint.setColor(Color.BLACK);
for(int i = 10; i < 400; i = i + 10)
{
try
{
// To slow the for loop down, can change 100 accordingly or remove altogther
Thread.sleep(100);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
canvas.drawRect(0, i, 10, 0, paint); // this will make 10 x 10 square starting from bottom
invalidate();
}
What ever you do with canvas, even if you try for loop or invalidate, sleep, after all its drawing the shape in single stretch. I found the result in following way. May be it would be helpful for someone else, so adding the code here.
import android.os.Bundle;
import android.os.CountDownTimer;
import android.app.Activity;
import android.graphics.Color;
import android.util.Log;
import android.view.Menu;
public class AndroidDraw extends Activity {
private DrawView drawView;
private int height = 300;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_android_draw);
CountDownTimer timer = new CountDownTimer(2000, 50) {
#Override
public void onTick(long millisUntilFinished) {
height = height - 10;
drawView = new DrawView(AndroidDraw.this, height);
drawView.setBackgroundColor(Color.WHITE);
setContentView(drawView);
}
#Override
public void onFinish() {
}
};
timer.start();
}
}
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;
public class DrawView extends View {
Paint paint = new Paint();
private int height;
public DrawView(Context context, int height) {
super(context);
this.height = height;
}
#Override
public void onDraw(Canvas canvas) {
paint.setColor(Color.RED);
canvas.drawRect(30, height, 60, 300, paint );
}
}
I want to rotate circle continuously in canvas on android. i am drawing circle using canvas and i am rotate circle continuously.it is possible,if possible how do it
with code or example can help me with greatly appreciated!
Here's my code for draw circle on canvas:
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.View;
public class AnimationActivity extends Activity {
/** Called when the activity is first created. */
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(new SampleView(this));
}
public class SampleView extends View
{
public SampleView(Context context)
{
super(context);
// TODO Auto-generated constructor stub
}
#Override
protected void onDraw(Canvas canvas)
{
Paint mPaint = new Paint();
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeWidth(10);
mPaint.setColor(Color.RED);
canvas.drawCircle(75, 75, 75, mPaint);
}
}
}
Thanks in Advance!
You can use Animation to rotate the circle you've drawn (using Canvas). The code below works. I've modified your code and added necessary changes.
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.View;
public class AnimationActivity extends Activity {
public class SampleView extends View {
Paint mPaint = new Paint();
private Animation anim;
public SampleView(Context context) {
super(context);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeWidth(10);
mPaint.setColor(Color.RED);
}
private void createAnimation(Canvas canvas) {
anim = new RotateAnimation(0, 360, getWidth()/2, getHeight()/2);
anim.setRepeatMode(Animation.RESTART);
anim.setRepeatCount(Animation.INFINITE);
anim.setDuration(10000L);
startAnimation(anim);
}
protected void onDraw(Canvas canvas) {
int cx = getWidth()/2; // x-coordinate of center of the screen
int cy = getHeight()/2; // y-coordinate of the center of the screen
// Starts the animation to rotate the circle.
if (anim == null)
createAnimation(canvas)
canvas.drawCircle(cx, cy, 150, mPaint); // drawing the circle.
}
}
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new SampleView(this));
}
}
Enjoy!
canvas.rotate(-rotate_angle, rotate_center_x, rotate_center_y);
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.RED);
RectF oval3 = new RectF(rotate_center_x-150, rotate_center_y-50, rotate_center_x+150, rotate_center_y+50);
canvas.drawOval(oval3, paint);
//resume original angle
canvas.rotate(rotate_angle, rotate_center_x, rotate_center_y);
For More Information, click here.. :)
I am used this from the android developers but don't understand why it force closes:
package com.example.shapedrawable.CustomDrawableView;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.OvalShape;
import android.view.View;
public class CustomDrawableViewActivity extends View {
private ShapeDrawable mDrawable;
public CustomDrawableViewActivity(Context context) {
super(context);
int x = 10;
int y = 10;
int width = 300;
int height = 50;
mDrawable = new ShapeDrawable(new OvalShape());
mDrawable.getPaint().setColor(Color.BLUE);
mDrawable.setBounds(x, y, x + width, y + height);
}
protected void onDraw(Canvas canvas) {
mDrawable.draw(canvas);
}
}
You don't say where it force closes which is always useful information, but I assume it's at this line:
mDrawable.getPaint().setColor(Color.BLUE);
getPaint() will return null until you call setPaint(). Try this:
Paint paint = new Paint();
paint.setColor(Color.BLUE);
mDrawable.setPaint(paint);
I am new to Android. When i run this code, only one circle is displayed. If i remove view1, then view2 is displayed. but they are never displayed together!!! why is that?
Any help would be appreciated.
thanks
package com.dots;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
public class Dots1Activity extends Activity
{
private static final String TAG = "DotsActivity";
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LinearLayout ll = new LinearLayout(this);
ll.setOrientation(LinearLayout.HORIZONTAL);
TextView label = new TextView(this);
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
label.setText("Click the circle!");
CustomDrawableView view1 = new CustomDrawableView(this, 100, 100, 50, Color.RED);
CustomDrawableView view2 = new CustomDrawableView(this, 200, 200, 25, Color.GREEN);
CustomDrawableView view3 = new CustomDrawableView(this, 300, 300, 10, Color.WHITE);
ll.addView(label, layoutParams);
ll.addView(view1, layoutParams);
ll.addView(view2, layoutParams);
ll.addView(view3, layoutParams);
setContentView(ll);
}
}
class CustomDrawableView extends View implements OnClickListener{
private Context context;
private int x, y, radius, color;
public CustomDrawableView(Context context, int x, int y, int radius, int color) {
super(context);
this.context = context;
this.x = x;
this.y =y;
this.radius = radius;
this.color = color;
setOnClickListener(this);
}
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
this.setBackgroundColor(Color.LTGRAY);
Paint paint = new Paint (Paint.ANTI_ALIAS_FLAG);
paint.setColor(color);
canvas.drawCircle(x, y, radius, paint);
}
public void onClick(View v) {
Toast.makeText(this.context,
x+"-"+y+"-"+radius,
Toast.LENGTH_SHORT).show();
}
}
ll.setOrientation(LinearLayout.HORIZONTAL);
They are put next to each other. You can't see them, because your display isn't width naught. Put them in a HorizontalScrollView or make them aper VERTICAL.
I'm not sure if this takes effect here, but i found this on the Android Documentation:
Note that the framework will not draw
views that are not in the invalid
region. To force a view to draw, call
invalidate().
Try if this solves your problem (for the moment I guess).
About your Code
Something i noticed: The implemented interface for the onClickListener is View.OnClickListener:
class CustomDrawableView extends View implements View.OnClickListener{ [...] }
How to solve the Problem
I looked around on the Android Docs and found this. They mantioned the method onMeasure(), which:
Measure the view and its content to
determine the measured width and the
measured height.
So I added it to your custom CustomDrawableView-class. Unfortuandly, you can't pass the super.onMeasure()-method simple integers, you'll need to decode them first, using the View.MeasureSpec-class:
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
super.onMeasure(View.MeasureSpec.makeMeasureSpec(100, View.MeasureSpec.EXACTLY),
View.MeasureSpec.makeMeasureSpec(100, View.MeasureSpec.EXACTLY));
}
In the Example, I set both width and height to 100px. Also, I did some other improvements on your code:
Dots1Activity-class
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.widget.LinearLayout;
import android.widget.TextView;
public class Dots1Activity extends Activity
{
private static final String TAG = "DotsActivity";
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LinearLayout ll = new LinearLayout(this);
ll.setOrientation(LinearLayout.VERTICAL);
TextView label = new TextView(this);
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
label.setText("Click the circle!");
CustomDrawableView view1 = new CustomDrawableView(this, 50, 50, 50, Color.RED);
CustomDrawableView view2 = new CustomDrawableView(this, 75, 75, 25, Color.GREEN);
CustomDrawableView view3 = new CustomDrawableView(this, 85, 85, 10, Color.WHITE);
ll.addView(label, layoutParams);
ll.addView(view1, layoutParams);
ll.addView(view2, layoutParams);
ll.addView(view3, layoutParams);
setContentView(ll);
}
}
CustomDrawableView-class
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.view.View;
import android.widget.Toast;
class CustomDrawableView extends View implements View.OnClickListener{
private Context context;
private int x, y, radius, color;
public CustomDrawableView(Context context, int x, int y, int radius, int color) {
super(context);
this.context = context;
this.x = x;
this.y =y;
this.radius = radius;
this.color = color;
setOnClickListener(this);
}
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(color);
canvas.drawCircle(x, y, radius, paint);
}
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
super.onMeasure(View.MeasureSpec.makeMeasureSpec(100, View.MeasureSpec.EXACTLY),
View.MeasureSpec.makeMeasureSpec(100, View.MeasureSpec.EXACTLY));
}
public void onClick(View v) {
Toast.makeText(this.context,
x+"-"+y+"-"+radius,
Toast.LENGTH_SHORT).show();
}
}
This code compiles, shows all the circles and the onClick-Event works, too.
Although I have to say it was a bit of a challenge and I'm grateful for it.
change the orientation of you layout to vertical like this :
ll.setOrientation(LinearLayout.VERTICAL);