I am trying to draw a text at the centre of canvas, Since canvas starts drawing text at BaseLine, I am not able to Place it at centre. If i can get the baseLine, then i can calculate the centre.
I have tried with paint.getFontMetrics() this gives ascent and descent but not baseLine.
Did you try this code
private void drawCenter(Canvas canvas, Paint paint, String text) {
canvas.getClipBounds(r);
int cHeight = r.height();
int cWidth = r.width();
paint.setTextAlign(Paint.Align.LEFT);
paint.getTextBounds(text, 0, text.length(), r);
float x = cWidth / 2f - r.width() / 2f - r.left;
float y = cHeight / 2f + r.height() / 2f - r.bottom;
canvas.drawText(text, x, y, paint);
}
All the calculations of paint.getFontMetrics() will happen with respect to baseLine. So if i just subtract (getMeasuredHeight() / 2f) - (fontMetrics.ascent / 2f) it will draw from center
Related
I'm trying to animate a background in a game I'm making.
https://imgur.com/kQGWsLu
Should look like this(terrible recording quality)
My first attempt work well on my phone but a lot of people saw their fps cut in half:
public void draw(Canvas canvas, Paint paint) {
if (mPaint == null) {
mPaint = new Paint();
mPaint.setColor(Color.GRAY);
mPaint.setStrokeWidth(1);
mPaint.setAntiAlias(true);
mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
mPaint.setShader(new RadialGradient(canvas.getWidth() / 4, canvas.getHeight() / 3,
Math.max(1, canvas.getHeight() / 2), Color.rgb(5, 12, 127), Color.rgb(32, 36, 100), Shader.TileMode.REPEAT));
}
width = canvas.getWidth();
height = canvas.getHeight();
canvas.save();
rotation += 4;
if (rotation > 360)
rotation = 0;
canvas.rotate(rotation, width / 2, height / 2);
canvas.drawCircle(width / 2, height / 2, height * 1.3f, mPaint);
canvas.restore();
}
So now I'm thinking about of pre rendering a image and drawing it as a bitmap that covers the screen and rotates instead. I also cut the calculations to only update every other frame instead.
public void draw(Canvas canvas, Paint paint) {
if (!initiated) {
centerX = (int) (canvas.getWidth() / 2);
centerY = (int) (canvas.getHeight() / 2);
width = (int) (canvas.getWidth() * 2f);
height = (int) (canvas.getHeight() * 2f);
map = factory.GFX().getBackground();
initiated = true;
}
if (!skipUpdate) {
x = CalculatorService.getXCircle(rotation, distance, centerX);
y = CalculatorService.getYCircle(rotation, distance, centerY);
body.set((int) x - width / 2,
(int) y - height / 2,
(int) x + (width / 2),
(int) y + (height / 2));
rotation += rotationSpeed;
if (rotation > 360)
rotation = 0;
}
skipUpdate = !skipUpdate;
canvas.drawBitmap(map, null, body, paint);
}
Though since the image is small in size 320*320 I had to scale it up and draw it bigger then the screen to avoid it moving out of bounds and showing the basic black background, and I'm not sure if this is really a improvement, do anyone have a better way of doing it or any advice on how I can improve?
i am drawing canavasarc but some how it always start from left i am it should start from middle
float x = 0.25f;
final float radius = x * (new Float(dpi));
mRadius = Math.round(radius) + 20;
mRect = new RectF(
getWidth() + mStrokeWidth, getWidth() + mStrokeWidth, getWidth() + (mRadius / 2) - mStrokeWidth, getWidth() + (mRadius / 2) - mStrokeWidth
);
canvas.drawArc(mRect, lastDegree, mSectionDegree, false, mPaint);
why this view always starts from left even i have given gravity centre still
float Degree = 270 + (mGap / 2);
for (int i = 0; i < mTotalSections; i++) {
fillColor(i);
canvas.drawArc(mRect, Degree, mDegree, false, mPaint);
Degree += mDegree + mGap;
Paint mPaint1 = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint1.setStrokeWidth(1);
mPaint1.setStyle(Paint.Style.FILL);
mPaint1.setAntiAlias(true);
mPaint1.setTextSize(15 * getResources().getDisplayMetrics().density);
mPaint1.setColor(getResources().getColor(black));
mPaint1.setTextAlign(Paint.Align.CENTER);
canvas.drawText(text, mRect.centerX(), mRect.centerY(), mPaint1);
}
I'm not sure about what you want to do but your rect looks weird. A rect more like that should would be better:
mRect = new RectF(
0 + mStrokeWidth, 0 + mStrokeWidth, getWidth() - mStrokeWidth, getHeight - mStrokeWidth
);
But a little draw about what you want and the values of your angle would be perfect ;). I will edit my answer if you provide it.
Edit:
So if you want a circle in the middle of your custom view you can do something like that:
RectF mRect = new RectF(
50 + mStrokeWidth, 50 + mStrokeWidth, getWidth() -50 - mStrokeWidth, getHeight() -50 - mStrokeWidth
);
canvas.drawArc(mRect, 0,360,false,paint);
result(the blue lines are the limit of my view):
You have to modify the 50 to fit what you want ;).
If you want an arc that stick to the edges with an angle of 180 degrees:
RectF mRect = new RectF(
mStrokeWidth, mStrokeWidth, getWidth() - mStrokeWidth, getHeight() - mStrokeWidth
);
canvas.drawArc(mRect, 0,180,false,paint);
Result:
Let me know if you need something else.
I have a custom font String (Font-Awesome Icon) and I want to draw it into a FloatingActionButton. For this reason I must convert the String to a Drawable like this.
The problem is that the icon is never centered, even if I try something like this:
public override void Draw(global::Android.Graphics.Canvas canvas)
{
Rect bounds = new Rect();
paint.GetTextBounds(text, 0, text.Length, bounds);
float x = (canvas.Width / 2f) - (bounds.Width() / 2f)
float y = (canvas.Height / 2f) - (bounds.Height() / 2f);
canvas.DrawText(text, x, y, paint);
}
The result will be something like this:
I can't figure out the problem.
Thanks in advance.
Edit:
If I do GetBounds, this is the result:
I want to draw an arc using the method: .Canvas.drawArc(RectF oval, float startAngle, float sweepAngle, boolean useCenter, Paint paint)
I have two points on the circle and the circle center point and radius.
What exactly do I need to set in the oval rect and how to calculate the startAngle and sweepAngle?
I tried the code below:
m_radiusRect.set(x1, Math.min(y1, y2), x2, Math.max(y1,y2));
float startAngle = (float)((Math.toDegrees( Math.atan2(x1 - 360.0, 360.0 - y1) ) + 360.0) % 360.0);
float sweepAngle = (float)((Math.toDegrees( Math.atan2(x2 - 360.0, 360.0 - y2) ) + 360.0) % 360.0) - startAngle;
canvas.drawArc(m_radiusRect, startAngle, sweepAngle, false, m_paint);
See this answer and find the angle of a point from center.
Based on that find the two angles for x1 and x2 says a1 and a2.
then,
sweepAngle = a2 - a1;
startAngle = a1;
Edited
The formula given in link looks not working since it does not consider center.
Here center is (cx, cy)
float startAngle = (int) ((float) Math.toDegrees( Math.atan2(x1 - cx, y1 - cy)));
float sweepAngle = (int) ((float) Math.toDegrees( Math.atan2(x2 - cx, y2 - cy))) - startAngle;
Rect rect = new Rect();
rect.left = (int) (cx - radius);
rect.top = (int) (cy - radius);
rect.right = (int) (cx + radius);
rect.bottom = (int) (cy + radius);
What is the best way for draw a number inside circle drawed on canvas by drawCircle?
Then this circle can be dragged by user, when circle is empty I don´t have problems.
This will draw text centered at centerX, centerY
Rect rect = new Rect();
paint.getTextBounds(text, 0, text.length(), rect);
float x = centerX - rect.width() / 2;
FontMetrics fm = paint.getFontMetrics();
float y= centerY - (fm.descent + fm.ascent) / 2;
canvas.drawText(text, x, y, paint);