Develop Reference

drawing line with arrow between 2 buttons

I have 12 lines I've created using the following class
public class LineView extends View {
private Paint paint = new Paint();
private PointF pointA,pointB;
// private void init() {
// paint.setColor(Color.BLACK);
// }
public LineView(Context context) {
super(context);
// init();
}
public LineView(Context context, AttributeSet attrs) {
super(context, attrs);
// init();
}
public LineView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// init();
}
#SuppressLint("ResourceAsColor")
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
int color = R.color.GradientStart;
paint.setColor(color);
paint.setColor(Color.BLUE);
paint.setStrokeWidth(5);
//canvas.drawLine(x1, y1, x2, y2, paint);
canvas.drawLine(pointA.x, pointA.y, pointB.x, pointB.y, paint);
}
public void setPointA(PointF point){
pointA=point;
}
public void setPointB(PointF point){
pointB=point;
}
public void draw(){
invalidate();
requestLayout();
}
}
Instead of lines I what lines with arrows. The line with arrow will be drawn between buttons.
How can I add arrows to one end of my lines?
It would like like this when complete.
thanks
JN

I found two way for achieve your requirement.
1) To use nine patch image. I have tried to make nine patch image for you please use it
2) You can use vector image for it.
Tell me still you not getting solution.

how to draw rectangle canvas?

In this example code I give a nice square in the form I want. canvas.drawRect (100, 300, 600, 800, paint); values work. But what I want is to call these values from the Activity class. So I want to send these values to the Draw class in the activity class. How can I do that ? For example, I want to send an activity class as drawRect (100,100,100,100, Color.BLUE). I do not want to write these values in the Draw class.
Draw.java
public class Draw extends View {
Paint paint;
Path path;
public Draw(Context context) {
super(context);
init();
}
public Draw(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public Draw(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
public void init(){
paint = new Paint();
paint.setColor(Color.BLACK);
paint.setStrokeWidth(10);
paint.setStyle(Paint.Style.STROKE);
}
#Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
canvas.drawRect(100, 300, 600, 800, paint);
}
}
Activity.java
constraintLayout=findViewById(R.id.constraint);
Draw draw = new Draw(this);
constraintLayout.addView(draw);

You need to make method and pass value from activity to draw class:-
Draw draw = new Draw(this,100, 300, 600, 800);
constraintLayout.addView(draw);
Draw class
public class Draw extends View {
Paint paint;
Path path;
float left;
float top;
float right;
float bottom;
public Draw(Context context,float left, float top, float right, float bottom) {
super(context);
this.left = left;
this.top = top;
this.right = right;
this.bottom = bottom;
init();
}
public Draw(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public Draw(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
public void init(){
paint = new Paint();
paint.setColor(Color.BLACK);
paint.setStrokeWidth(10);
paint.setStyle(Paint.Style.STROKE);
}
#Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
canvas.drawRect(left, top, right, bottom, paint);
}
}

You can create local variables for the bounds and set them using setters or init function before adding that view to a viewgroup.( constraintLayout.addView(draw) in your case

CustomTextView canvas not drawing

Drawable not drawing in custom TextView. Can anyone please help me in sorting the problem out. What i was trying to build is a texview that shows progress. The below mention code is just a sample.
public class ProgressableTextview extends TextView {
Paint mPaint;
int mProgress = 70;
int maxProgress = 100;
int mRadiud = 10;
public ProgressableTextview(Context context) {
super(context);
init();
}
public ProgressableTextview(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public ProgressableTextview(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
public void init(){
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setColor(Color.BLACK);
mPaint.setStyle(Paint.Style.FILL);
}
#Override
public void onDraw(Canvas canvas) {
canvas.drawColor(Color.GRAY);
canvas.drawRect(0, 0, (mProgress/maxProgress)*getWidth(), getMeasuredHeight(), mPaint);
canvas.save();
canvas.translate(getLeft(), 0);
super.onDraw(canvas);
canvas.restore();
}
}

Ok i figured out what was the problem, it was the mistake in drawRect function. drawRect function need to changed as :
canvas.drawRect(0, 0, ((float) mProgress/maxProgress) * getWidth(), getMeasureHeight(), mPaint);
since mProgress was a integer dividing it by integer returns zero and that was the problem.

How do you overline numbers in android xml?

I am developing a maths app in which i have to use numbers with bar on top. check this link http://en.wikipedia.org/wiki/Overline
Also how to use Exponentiation like in the following link http://en.wikipedia.org/wiki/Exponentiation in xml file.

This is not the perfect solution but it will give you the idea for text overline.
public class OverLineTextView extends TextView {
private Paint paint;
public OverLineTextView(Context context) {
super(context);
init();
}
public OverLineTextView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public OverLineTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init() {
paint = new Paint();
paint.setAntiAlias(true);
paint.setColor(Color.GREEN);
paint.setStyle(Style.STROKE);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
float width = getPaint().measureText(getText().toString());
canvas.drawLine(getTotalPaddingLeft(), getTotalPaddingTop() + 1,
getTotalPaddingLeft() + width, getTotalPaddingTop() + 1, paint);
}
}

Create Custom View

I am trying to achieve the effect of creating a view with a custom shape(almost rectangular).
Here is what i tried to do:
public class CustomHeaderview extends View {
public CustomHeaderview(Context context) {
super(context);
}
public CustomHeaderview(Context context, AttributeSet attrs) {
super(context, attrs);
}
public CustomHeaderview(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
Paint paint = new Paint();
#Override
public void draw(Canvas canvas) {
paint.setColor(Color.GRAY);
paint.setStyle(Style.FILL);
Path wallpath = new Path();
wallpath.reset(); // only needed when reusing this path for a new build
wallpath.moveTo(100, 100); // used for first point
wallpath.lineTo(100, 200);
wallpath.lineTo(200, 200);
wallpath.lineTo(150, 100);
wallpath.lineTo(100, 100);// there is a setLastPoint action but i found it not to work as expected
canvas.drawPath(wallpath, paint);
super.draw(canvas);
}
}
and the XML:
<CustomHeaderview
android:layout_width="152dp"
android:layout_height="152dp" />
EDIT
Thanks Dmitry, it works perfectly now!

You providing fancy coordinates for you rectangle:
x1: 100
y1: 100
x2: 100
y2: 120
So, you're getting rectangle with 0 width, thats why it is invisible.