Hello everyone,
I need to draw some stuff in perspective and i need it to move it
around as well as moving the perspective effect, i found the nice
example polytopoly on the google samples, i made some changes to the
code, and i found out, the following issues:
– When drawing with some perspective point sometimes i will draw the
rectangles and fill them with all the content in perspective like i
wanted it to, but if i move this rectangle the content of the
rectangle will be draw in perspective but i cannot fill the rectangle.
– I found as well that setting the
paint.style(Paint.Style.FILL_AND_STROKE) it will draw and fill the
rectangle in some positions but not the others, and if i set the style
to just fill it wont fill anything.
– Does anyone know what am I doing wrong? or is this some bug in the
android framework. I don't understand why when i move horizontally my
boxes one of these boxes stops filling but not the other?
So when i have this peace of code:
canvas.save();
doDraw(canvas, new float[] { xpos, ypos, xpos+width, ypos, xpos+width,
ypos+height, xpos, ypos+height},
new float[] { xpos, ypos, xpos+width+10, ypos+10, xpos+width+10, ypos
+height, xpos, ypos+height+20});
canvas.restore();
that draws a box in perspective i can fill it in any horizontal and
vertical position, but only with the
mPaint.setStyle(Paint.Style.FILL_AND_STROKE) if I set it just to FILL
it will not fill.
if call this piece of code:
doDraw(canvas, new float[] { xpos, ypos, xpos+width, ypos, xpos+width,
ypos+height, xpos, ypos+height},
new float[] { xpos, ypos+15, xpos+width+15, ypos, xpos+width+15,
ypos+height+25, xpos, ypos+height});
canvas.restore();
when xpos>120 it will not fill the box, but everything inside is in
perspective.
Can anyone help me with this please, i really don't understand what
i'm doing wrong, if there is no way around could anyone give me some
hints on how to work around this, in a efficient way.
The class code is the bottom of this message:
Any help would be really appreciated.
Regards
Ricardo
Here it is my class;
/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.android.apis.graphics;
// Need the following import to get access to the app resources, since
this
// class is in a sub-package.
//import com.example.android.apis.R;
import android.app.Activity;
import android.content.Context;
import android.graphics.*;
import android.os.Bundle;
import android.view.View;
public class PolyToPoly extends GraphicsActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new SampleView(this));
}
private static class SampleView extends View {
private Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
private Matrix mMatrix = new Matrix();
private Paint.FontMetrics mFontMetrics;
int xpos=10;
int ypos=160;
int width=64;
int height=64;
private void doDraw(Canvas canvas, float src[], float dst[]) {
canvas.save();
mMatrix.setPolyToPoly(src, 0, dst, 0, src.length >> 1);
canvas.concat(mMatrix);
mPaint.setColor(Color.GRAY);
mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
Path path=new Path();
path.moveTo(xpos, ypos);
path.lineTo(xpos+width, ypos);
path.lineTo(xpos+width, ypos+height);
path.lineTo(xpos, ypos+height);
path.close();
canvas.drawPath(path, mPaint);
mPaint.setColor(Color.RED);
mPaint.setStyle(Paint.Style.FILL);
// how to draw the text center on our square
// centering in X is easy... use alignment (and X at
midpoint)
float x = xpos+width/2;
// centering in Y, we need to measure ascent/descent first
float y = ypos+height/2 - (mFontMetrics.ascent +
mFontMetrics.descent)/2;
canvas.drawText("blabla", x, y, mPaint);
canvas.restore();
}
public SampleView(Context context) {
super(context);
// for when the style is STROKE
mPaint.setStrokeWidth(4);
// for when we draw text
mPaint.setTextSize(13);
mPaint.setTextAlign(Paint.Align.CENTER);
mFontMetrics = mPaint.getFontMetrics();
}
@Override protected void onDraw(Canvas canvas) {
Paint paint = mPaint;
canvas.drawColor(Color.WHITE);
canvas.save();
doDraw(canvas, new float[] { xpos, ypos, xpos+width, ypos,
xpos+width, ypos+height, xpos, ypos+height},
new float[] { xpos, ypos, xpos+width+10, ypos+10, xpos
+width+10, ypos+height, xpos, ypos+height+20});
canvas.restore();
//
canvas.save();
xpos=150;
doDraw(canvas, new float[] { xpos, ypos, xpos+width, ypos,
xpos+width, ypos+height, xpos, ypos+height},
new float[] { xpos, ypos+15, xpos+width+15, ypos, xpos
+width+15, ypos+height+25, xpos, ypos+height});
canvas.restore();
}
}
}
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