Custom Color picker in android

Here i wrote a code with help of AndroidDeveloper'sBestGuide.It is just concept of implement canvas with a dialogbox.
We create different color by using Canvas.and then we select different color with the help of canvas.
With the help of this example ,you will also read how to create a custom diaolog




For more information about canvas you can write in comment.I will explain when ever i will be free.Or refer to Go to this link
1)Create One XML file in res/layout/main.xml

     <?xml version="1.0" encoding="UTF-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="20dip" android:id="@+id/main"
    android:orientation="vertical">
    <Button android:layout_width="wrap_content"         android:layout_height="wrap_content"
        android:layout_gravity="center" android:text="Change Background"
        android:id="@+id/change_color"/>
</LinearLayout>

2)create One activity and register in manifest file

 package com.android.gesture.builder.ahmad;

import com.android.Dialog.ColorPickerDialog;
import com.android.Dialog.ColorPickerDialog.OnColorChangedListener;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.Toast;

public class ColorPicker extends Activity{

    private LinearLayout ll;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Button btn=(Button) findViewById(R.id.change_color);
        ll=(LinearLayout) findViewById(R.id.main);
        btn.setOnClickListener(new OnClickListener() {
          
            @Override
            public void onClick(View v) {
                ColorPickerDialog cpd=new ColorPickerDialog(ColorPicker.this, listener, 0);
                cpd.show();
            }
        });
     }
     @Override
    protected void onResume() {
        super.onResume();
        ll.setBackgroundColor(ColorAh);
      
    }
   
    OnColorChangedListener listener=new OnColorChangedListener() {
            @Override
            public void colorChanged(int color) {
                Toast.makeText(ColorPicker.this, ""+color, Toast.LENGTH_LONG).show();
                ColorAh=color;
                ll.setBackgroundColor(ColorAh);
            }
        };
      
    private int ColorAh=Color.BLACK;
}

3)Now create a custom dialog
package com.android.Dialog;


import android.os.Bundle;
import android.app.Dialog;
import android.content.Context;
import android.graphics.*;
import android.view.MotionEvent;
import android.view.View;

public class ColorPickerDialog extends Dialog {

    public interface OnColorChangedListener {
        void colorChanged(int color);
    }

    private OnColorChangedListener mListener;
    private int mInitialColor;

    private static class ColorPickerView extends View {
        private Paint mPaint;
        private Paint mCenterPaint;
        private final int[] mColors;
        private OnColorChangedListener mListener;

        ColorPickerView(Context c, OnColorChangedListener l, int color) {
            super(c);
            mListener = l;
            mColors = new int[] {
                0xFFFF0000, 0xFFFF00FF, 0xFF0000FF, 0xFF00FFFF, 0xFF00FF00,
                0xFFFFFF00, 0xFFFF0000
            };
            Shader s = new SweepGradient(0, 0, mColors, null);

            mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            mPaint.setShader(s);
            mPaint.setStyle(Paint.Style.STROKE);
            mPaint.setStrokeWidth(32);

            mCenterPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
            mCenterPaint.setColor(color);
            mCenterPaint.setStrokeWidth(5);
        }

        private boolean mTrackingCenter;
        private boolean mHighlightCenter;

        @Override
        protected void onDraw(Canvas canvas) {
            float r = CENTER_X - mPaint.getStrokeWidth()*0.5f;

            canvas.translate(CENTER_X, CENTER_X);

            canvas.drawOval(new RectF(-r, -r, r, r), mPaint);
            canvas.drawCircle(0, 0, CENTER_RADIUS, mCenterPaint);

            if (mTrackingCenter) {
                int c = mCenterPaint.getColor();
                mCenterPaint.setStyle(Paint.Style.STROKE);

                if (mHighlightCenter) {
                    mCenterPaint.setAlpha(0xFF);
                } else {
                    mCenterPaint.setAlpha(0x80);
                }
                canvas.drawCircle(0, 0,
                                  CENTER_RADIUS + mCenterPaint.getStrokeWidth(),
                                  mCenterPaint);

                mCenterPaint.setStyle(Paint.Style.FILL);
                mCenterPaint.setColor(c);
            }
        }

        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            setMeasuredDimension(CENTER_X*2, CENTER_Y*2);
        }

        private static final int CENTER_X = 100;
        private static final int CENTER_Y = 100;
        private static final int CENTER_RADIUS = 32;

        private int floatToByte(float x) {
            int n = java.lang.Math.round(x);
            return n;
        }
        private int pinToByte(int n) {
            if (n < 0) {
                n = 0;
            } else if (n > 255) {
                n = 255;
            }
            return n;
        }

        private int ave(int s, int d, float p) {
            return s + java.lang.Math.round(p * (d - s));
        }

        private int interpColor(int colors[], float unit) {
            if (unit <= 0) {
                return colors[0];
            }
            if (unit >= 1) {
                return colors[colors.length - 1];
            }

            float p = unit * (colors.length - 1);
            int i = (int)p;
            p -= i;

            // now p is just the fractional part [0...1) and i is the index
            int c0 = colors[i];
            int c1 = colors[i+1];
            int a = ave(Color.alpha(c0), Color.alpha(c1), p);
            int r = ave(Color.red(c0), Color.red(c1), p);
            int g = ave(Color.green(c0), Color.green(c1), p);
            int b = ave(Color.blue(c0), Color.blue(c1), p);

            return Color.argb(a, r, g, b);
        }

        private int rotateColor(int color, float rad) {
            float deg = rad * 180 / 3.1415927f;
            int r = Color.red(color);
            int g = Color.green(color);
            int b = Color.blue(color);

            ColorMatrix cm = new ColorMatrix();
            ColorMatrix tmp = new ColorMatrix();

            cm.setRGB2YUV();
            tmp.setRotate(0, deg);
            cm.postConcat(tmp);
            tmp.setYUV2RGB();
            cm.postConcat(tmp);

            final float[] a = cm.getArray();

            int ir = floatToByte(a[0] * r +  a[1] * g +  a[2] * b);
            int ig = floatToByte(a[5] * r +  a[6] * g +  a[7] * b);
            int ib = floatToByte(a[10] * r + a[11] * g + a[12] * b);

            return Color.argb(Color.alpha(color), pinToByte(ir),
                              pinToByte(ig), pinToByte(ib));
        }

        private static final float PI = 3.1415926f;

        @Override
        public boolean onTouchEvent(MotionEvent event) {
            float x = event.getX() - CENTER_X;
            float y = event.getY() - CENTER_Y;
            boolean inCenter = java.lang.Math.sqrt(x*x + y*y) <= CENTER_RADIUS;

            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    mTrackingCenter = inCenter;
                    if (inCenter) {
                        mHighlightCenter = true;
                        invalidate();
                        break;
                    }
                case MotionEvent.ACTION_MOVE:
                    if (mTrackingCenter) {
                        if (mHighlightCenter != inCenter) {
                            mHighlightCenter = inCenter;
                            invalidate();
                        }
                    } else {
                        float angle = (float)java.lang.Math.atan2(y, x);
                        // need to turn angle [-PI ... PI] into unit [0....1]
                        float unit = angle/(2*PI);
                        if (unit < 0) {
                            unit += 1;
                        }
                        mCenterPaint.setColor(interpColor(mColors, unit));
                        invalidate();
                    }
                    break;
                case MotionEvent.ACTION_UP:
                    if (mTrackingCenter) {
                        if (inCenter) {
                            mListener.colorChanged(mCenterPaint.getColor());
                        }
                        mTrackingCenter = false;    // so we draw w/o halo
                        invalidate();
                    }
                    break;
            }
            return true;
        }
    }

    public ColorPickerDialog(Context context,
                             OnColorChangedListener listener,
                             int initialColor) {
        super(context);

        mListener = listener;
        mInitialColor = initialColor;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        OnColorChangedListener l = new OnColorChangedListener() {
            public void colorChanged(int color) {
                mListener.colorChanged(color);
                dismiss();
            }
        };

        setContentView(new ColorPickerView(getContext(), l, mInitialColor));
        setTitle("Pick a Color");
    }
}

                                Screen Shot how it will work                                               
                                             

                         Now change Change color using color picker

Now Select color

Plan design in best way for Multiple Screen size

Planning for Multiple Touchscreen Sizes

While you are designing application for mobile screen then we have remember one thing that we have limited space to show and we have to utilized it as possible..

I take reference from android authorize site  to write my article. i used same image 

Group Screens with Multi-pane Layouts

3 to 4-inch screens are generally only suitable for showing a single vertical pane of content at a time, be it a list of items, or detail information about an item, etc. Thus on such devices, screens generally map one-to-one with levels in the information hierarchy (categories → object list → object detail).

Larger screens such as those found on tablets and TVs, on the other hand, generally have much more available screen space and are able to present multiple panes of content. In landscape, panes are usually ordered from left to right in increasing detail order. Users are especially accustomed to multiple panes on larger screens from years and years of desktop application and desktop web site use. Many desktop applications and websites offer a left-hand navigation pane or use a master/detail two-pane layout.

The following figures demonstrate some of the problems that can arise when moving a UI (user interface) design into a larger layout and how to address these issues with multi-pane layouts:

Figure 1. Single pane layouts on large screens in landscape lead to awkward whitespace and exceedingly long line lengths.

Figure 2. Multi-pane layouts in landscape result in a better visual balance while offering more utility and legibility.

Implementation Note: After deciding on the screen size at which to draw the line between single-pane and multi-pane layouts, you can provide different layouts containing one or multiple panes for devices in varying screen size buckets (such as large/xlarge) or varying minimum screen widths (such assw600dp).

Implementation Note: While a single screen is implemented as an Activity subclass, individual content panes can be implemented as Fragment subclasses. This maximizes code re-use across different form factors and across screens that share content.

Design for Multiple Tablet Orientations

Although we haven't begun arranging user interface elements on our screens yet, this is a good time to consider how your multi-pane screens will adapt to different device orientations. Multi-pane layouts in landscape work quite well because of the large amount of available horizontal space. However, in the portrait orientation, your horizontal space is more limited, so you may need to design a separate layout for this orientation.

Below are a few common strategies for creating portrait tablet layouts.

• Stretch 
  The most straightforward strategy is to simply stretch each pane's width to best present the content in each pane in the portrait orientation. Panes could have fixed widths or take a certain percentage of the available screen width.
• Expand/collapse 
  A variation on the stretch strategy is to collapse the contents of the left pane when in portrait. This works quite well with master/detail panes where the left (master) pane contains easily collapsible list items. An example would be for a realtime chat application. In landscape, the left list could contain chat contact photos, names, and online statuses. In portrait, horizontal space could be collapsed by hiding contact names and only showing photos and online status indicator icons.
• Show/Hide 
  In this scenario, the left pane is completely hidden in portrait mode. However, to ensure the functional parity of your screen in portrait and landscape, the left pane should be made available via an onscreen affordance (such as a button). It's usually appropriate to use the Up button in the Action Bar to show the left pane, as is discussed in a later lesson.
• Stack 
  The last strategy is to vertically stack your normally horizontally-arranged panes in portrait. This strategy works well when your panes aren't simple text-based lists, or when there are multiple blocks of content running along the primary content pane. Be careful to avoid the awkward whitespace problem discussed above when using this strategy.

Group Screens in the Screen Map

Now that we are able to group individual screens together by providing multi-pane layouts on larger-screen devices, let's apply this technique to our exhaustive screen map from the previous lesson to get a better sense of our application's hierarchy on such devices:

Figure 3. Updated example news application screen map for tablets.

In the next lesson we discuss descendant and lateral navigation, and explore more ways of grouping screens to maximize the intuitiveness and speed of content access in the application's user interface.

Designing Effective Navigation

One of the very first steps to designing and developing an Android application is to determine what users are able to see and do with the app. Once you know what kinds of data users are interacting with in the app, the next step is to design the interactions that allow users to navigate across, into, and back out from the different pieces of content within the app.

This class shows you how to plan out the high-level screen hierarchy for your application and then choose appropriate forms of navigation to allow users to effectively and intuitively traverse your content. Each lesson covers various stages in the interaction design process for navigation in Android applications, in roughly chronological order. After going through the lessons in this class, you should be able to apply the methodology and navigation paradigms outlined here to your own applications, providing a coherent navigation experience for your users.

Lessons

Planning Screens and Their Relationships

Learn how to choose which screens your application should contain. Also learn how to choose which screens should be directly reachable from others. This lesson introduces a hypothetical news application to serve as an example for later lessons.

Planning for Multiple Touchscreen Sizes

Learn how to group related screens together on larger-screen devices to optimize use of available screen space.

Providing Descendant and Lateral Navigation

Learn about techniques for allowing users to navigate deep into, as well as across, your content hierarchy. Also learn about pros and cons of, and best practices for, specific navigational UI elements for various situations.

Providing Ancestral and Temporal Navigation

Learn how to allow users to navigate upwards in the content hierarchy. Also learn about best practices for the BACK button and temporal navigation, or navigation to previous screens that may not be hierarchically related.

Putting it All Together: Wireframing the Example App

Learn how to create screen wireframes (low-fidelity graphic mockups) representing the screens in a news application based on the desired information model. These wireframes utilize navigational elements discussed in previous lessons to demonstrate intuitive and efficient navigation.