I'm new to the Android SDK so I'm trying to figure this out. I have read the documentation and a text book and they haven't been particularly helpful in this matter.
I'm just trying to draw a simple rectangle in a linear layout on the screen. I can't get the shape to show up, however, when I add text to this layout in the same fashion, the text does show up. What am I missing?
package jorge.jorge.jorge;
import android.app.Activity;
import android.graphics.Color;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.RectShape;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
public class ShapesActivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ShapeDrawable rect = new ShapeDrawable(new RectShape());
rect.getPaint().setColor(Color.GREEN);
ImageView view1 = new ImageView(this);
view1.setImageDrawable(rect);
LinearLayout frame = (LinearLayout)findViewById(R.id.linear1);
frame.addView(view1);
// TextView tx = new TextView(this);
//
// tx.setText("Hello World");
//
// frame.addView(tx);
}
}
The Shape is usually used for making a background to some View. Its width and height is the same of the view that is using it. Then, if this view has no width and height, It'll have no width and height, too.
Basically, I think that your ImageView has no width and height, then it's invisible.
You can see how to set it programatically here:
Set ImageView width and height programmatically?
But, I recomend you to make the layout in XML's way.
Related
My variable hz is null, why is this?
code:
HorizontalScrollView hz = (HorizontalScrollView) findViewById((R.id.horizontalScrollView2));
hz.addView(imageView, params);
hz.setBackgroundColor(Color.BLACK);
// Show this layout in our activity.
ScrollView scrollView = (ScrollView) findViewById(R.id.scrollView);
setContentView(scrollView);
xml:
<ScrollView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/scrollView">
<HorizontalScrollView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/horizontalScrollView2">
<AbsoluteLayout
android:layout_width="1000dp"
android:layout_height="1000dp"
android:id="#+id/al"/>
</HorizontalScrollView>
</ScrollView>
Also it won't allow me to have my absoluteLayout within the horizontalScrollView. I'm trying to make a drawable area bigger than the screen size that you can scroll both up and down, where I will be drawing a board game board. Can someone give me a hand to get this drawable area set up? Thanks.
All code of my activity:
package com.example.btf.game;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.widget.HorizontalScrollView;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.ScrollView;
public class SplashScreen extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// We'll be creating an image that is 100 pixels wide and 200 pixels tall.
int width = 1000;
int height = 3000;
// Create a bitmap with the dimensions we defined above, and with a 16-bit pixel format. We'll
// get a little more in depth with pixel formats in a later post.
Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
// Create a paint object for us to draw with, and set our drawing color to blue.
Paint paint = new Paint();
paint.setColor(Color.BLUE);
// Create a new canvas to draw on, and link it to the bitmap that we created above. Any drawing
// operations performed on the canvas will have an immediate effect on the pixel data of the
// bitmap.
Canvas canvas = new Canvas(bitmap);
// Fill the entire canvas with a red color.
canvas.drawColor(Color.RED);
// Draw a rectangle inside our image using the paint object we defined above. The rectangle's
// upper left corner will be at (25,50), and the lower left corner will be at (75,150). Since we set
// the paint object's color above, this rectangle will be blue.
canvas.drawRect(25, 50, 75, 150, paint);
// In order to display this image in our activity, we need to create a new ImageView that we
// can display.
ImageView imageView = new ImageView(this);
// Set this ImageView's bitmap to the one we have drawn to.
imageView.setImageBitmap(bitmap);
// Create a simple layout and add our image view to it.
RelativeLayout layout = new RelativeLayout(this);
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT,
RelativeLayout.LayoutParams.WRAP_CONTENT);
params.addRule(RelativeLayout.CENTER_IN_PARENT);
// LinearLayout container = (LinearLayout) findViewById(R.id.container);
HorizontalScrollView hz = (HorizontalScrollView) findViewById((R.id.horizontalScrollView2));
hz.addView(imageView, params);
hz.setBackgroundColor(Color.BLACK);
// Show this layout in our activity.
ScrollView scrollView = (ScrollView) findViewById(R.id.scrollView);
setContentView(scrollView);
}
}
Your views are null because there are not a part of activity at time you're trying to get them through findViewById() method.
You need to call setContentView() before "finding" views and pass your xml layout in it: setContentView(R.layout.my_acitivty_layout)
I'm stucked in this for almost a month. I have a perfect chart in my android code using 'afreechart', however, the library does not seem to have support for exporting the chart as an image yet (since it's based on 'jfreechart' and this one does the job).
I tried to get the view of the chart, convert it into canvas and save using the compress functions of the bitmap library, however everytime i try this i get a totally black image as a result. I tried this same method and it works for the other views of my code (simple views, like linearlayout and relativelayout).
After that i tried to create a routine to make a screenshot of the chart activity and close that activity after that. But I couldn't find a way to do that by code, the closest i got was with monkeyrunner.
So i gave up of this idea and tried to look for other libraries, such as 'kichart', 'achartengine', etc, but none of them seem to do the job for, i'm freaking out and i thought that exporting the chart to an image wouldn't be that hard... any ideas?
When i set a background color for the layout, the returned image is a full rectangle with the color of the background, so it's getting the layout, just not the chart.
My Code:
package com.kichart;
import java.io.File;
import java.io.FileOutputStream;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.LinearLayout;
public class Main extends Activity {
LinearLayout ll;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
float[] values = new float[] { 2.0f,1.5f, 2.5f, 1.0f , 3.0f };
String[] verlabels = new String[] { "great", "ok", "bad" };
String[] horlabels = new String[] { "today", "tomorrow", "next week", "next month" };
GraphView graphView = new GraphView(this, values, "GraphViewDemo",horlabels, verlabels, GraphView.BAR);
ll = new LinearLayout(this);
ll.addView(graphView);
Draw2d d = new Draw2d(this);
setContentView(d);
//setContentView(graphView);
}
public class Draw2d extends View {
public Draw2d(Context context) {
super(context);
setDrawingCacheEnabled(true);
}
#Override
protected void onDraw(Canvas c) {
ll.setBackgroundColor(Color.WHITE);
ll.measure(MeasureSpec.getSize(ll.getWidth()), MeasureSpec.getSize(ll.getHeight()));
ll.layout(400, 400, 400, 400);
ll.draw(c);
try {
getDrawingCache().compress(Bitmap.CompressFormat.PNG, 100, new FileOutputStream(new File("/mnt/sdcard/graph2.png")));
} catch (Exception e) {
Log.e("Error--------->", e.toString());
}
super.onDraw(c);
}
}
}
You can get a image bitmap from a view by doing:
Bitmap bitmap;
chart.setDrawingCacheEnabled(true);
bitmap = Bitmap.createBitmap(chart.getDrawingCache());
chart.setDrawingCacheEnabled(false);
if you can't call getDrawingCache on the chart, try to place it inside a layout like RelativeLayout or something like that. and call it on the layout.
After that you can save it as a image..
If the image is still black, you need to make sure the chart is created before getting the bitmap.
Hope this will help you
I am beginner in android. And i could not understand differences between layouts. i want to make a button and next to button i want to set an image. So which layout should i have yo use and how can i set the positions.(Programitacilly)
You need to visit this page:
Common Layout Objects
You will want to use the LinearLayout - inside the linear layout you can place your button and image.
There's a good tutorial on how to use LinearLayout over here:
Android Developers-LinearLayout
If you are new to Android, I would recommend checking out the other "Hello *" tutorials over there.
Cemal wanted to see this done programatically. The above references are good for showing the XML versions. Here is a quick example of the button and image in a linear layout done entirely programtically.
package com.example.android.ProgramLinearActivity;
import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;
public class ProgramLinearActivity extends Activity {
private static final int HORIZONTAL = 0;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LinearLayout linearLayout = new LinearLayout(this);
linearLayout.setOrientation(HORIZONTAL); //HORIZONTAL is default but here for clarity
ImageView imageView = new ImageView(this);
imageView.setImageResource( R.drawable.icon);
Button button = new Button (this);
button.setText("Test");
linearLayout.addView(button);
linearLayout.addView(imageView);
setContentView(linearLayout);
}
}
Hit ctrl+space a lot in the eclipse editor to see tutorials on the other attributes for the button and imageview wigets.
Here is my unanswered question:
Add new item count to icon on button - Android
Basically I want to display "new" counts on top. I see it as overlaying some view over existing button. How this can be done?
Easiest thing to do is:
Use a RelativeLayout with layout_height and layout_width set to WRAP_CONTENT.
Put one Button into the RelativeLayout with layout_height and layout_width set to WRAP_CONTENT.
Add an ImageView into the RelativeLayout aligned to PARENT_TOP and PARENT_RIGHT and set the visibility to GONE.
Then you can simply set the ImageView's drawable to the appropriate count image and set the visibility to VISIBLE.
Ok here is what i'd do:
Create a custom control that extends button. I'm not going to do the pretty graphics for you but this will give you the basic idea:
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.widget.Button;
public class CounterButton extends Button{
protected int count=0;
protected final Paint myTextPaint = new Paint();
protected final Paint myCirclePaint = new Paint();
public CounterButton(Context context, AttributeSet attrs) {
super(context, attrs);
this.setBackgroundDrawable(getResources().getDrawable(android.R.drawable.ic_dialog_email));
this.myCirclePaint.setARGB(150, 255, 0, 0);
this.myTextPaint.setARGB(150, 255, 255, 255);
}
#Override
protected void onDraw(Canvas canvas) {
if(count!=0){
canvas.drawCircle((float) (this.getWidth()*.75), (float) (this.getHeight()*.4), this.getHeight()/5, myCirclePaint);
canvas.drawText(Integer.toString(count), (float) (this.getWidth()*.75), (float) (this.getHeight()*.4), this.myTextPaint);
}
}
}
Clean up the sizing of your text you draw, the circle positioning (and add a border etc) and you have a custom control. You could further extend it so you could set the background in xml or dynamically and you have a reusable control with a number counter in a circle.
then in your code you could do:
CounterButton cb=(CounterButton) findViewById(R.id.whateverYouGaveItInXML);
cb.count=SomeNewNumber;
cb.invalidate;
the invalidate will redraw the image with the new value in the circle.
I used a button in the event you want to have it clickable easily and all that - but you could just as easily extend view if you are just doing a view.
I am using RelativeLayout to position views at precise locations on the screen. This works as expected when using a view that say, draws a rectangle. But when using Android views like EditText, they are drawn shorter than specified by about 8 units. Clicking outside of the drawn EditText (but within the parameters specified by RelativeLayout) will, in fact, hit the EditText.
Here is some code to illustrate what I mean:
package com.DrawDemo;
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;
import android.widget.EditText;
import android.widget.RelativeLayout;
public class DrawDemo extends Activity
{
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
RelativeLayout l = new RelativeLayout(this);
RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(100,100);
lp.leftMargin = 50;
lp.topMargin = 50;
DemoView demoview = new DemoView(this);
l.addView(demoview, lp);
EditText editText = new EditText(this);
l.addView(editText, lp);
setContentView(l);
}
private class DemoView extends View
{
public DemoView(Context context)
{
super(context);
}
#Override protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
Paint paint = new Paint();
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.GREEN);
canvas.drawPaint(paint);
}
}
}
If you execute this, you will notice that the EditText is noticeably shorter than the rectangle. I've tried mucking with onMeasure, setMinimumXXX, and just about everything else I can think of. So far, the only thing that works with some level of success is to just add 8 or so pixels to the height (8 seems to work better than trying a percentage of the height).
Next task will be to step into the source but was wondering if somebody has already solved this.
Thanks.
It's just because of the actual EditText background image that's used. Buttons are the same way, for some reason Google decided to draw the 9-patch background images with some extra transparent padding pixels. Really, the only solution, if it's a problem, would be to draw your own 9-patch, or modify the existing Android 9-patch to remove the extra pixels.