It's an interface that works with transparency effects. As a sample I used an interface just like the iPhone one.
In this tutorial I am explaining how simple is working with transparency and animation on Windows Mobile.
In all this article I have been mentioning Alpha blending. Alpha blending is a convex combination of two colours allowing transparency effects.
In order to raise more interest in this article I added an animation (status bar), events notifications (battery, GPS signal, timer), fingered movement of the objects (unlock button) and the second part concerning buttons view and their respective interactions with mobile native programs.
As a project base I used an example by Alex Yakhnin that concerns, of course, the use of API AlphaBlend in c#.
As already mentioned, this program shows how to display bitmaps that have transparent or semitransparent pixels with c#.
I have chosen C#/.Net to make things simpler and we will be using Visual Studio 2005 as the IDE.
If you have a bit of understanding of writing with C# or C++ (Windows GDI) this reading can be quicker and useful.
]. The project contains:
and a lot of BMP files.
Originally I have released only one form, but successively I have split it in two to make things more clear and removed the Topbar from the
This is a sample with 4 different wallpapers, all included in the solution.
The forms are in full screen (WindowState = Maximize) for best image and I have overridden the
In order to draw the background, you need to clear the screen and put on it (in the right order) your back ground first and the transparency object after. In the end you can add the items that require interaction.
Drawing off screen
In order to draw quicker, I drew all the controls off screen (in memory) in advance and at the end I have put them on the screen.
protected override void OnPaint(PaintEventArgs e)
gxBuffer = Graphics.FromImage(offBitmap);
e.Graphics.DrawImage(offBitmap, 0, 0);
Draw with transparency
In order to draw the alpha I used the DrawAlpha that uses the P/Invoke to
public class PlatformAPIs
extern public static Int32 AlphaBlend(
IntPtr hdcDest, Int32 xDest, Int32yDest, Int32 cxDest, Int32 cyDest,
IntPtr hdcSrc, Int32 xSrc, Int32 ySrc, Int32 cxSrc, Int32 cySrc,
private void DrawAlpha(Graphics gx, Bitmap image, byte transp, int x, int y)
using (Graphics gxSrc = Graphics.FromImage(image))
IntPtr hdcDst = gx.GetHdc();
IntPtr hdcSrc = gxSrc.GetHdc();
BlendFunction blendFunction = new BlendFunction();
blendFunction.BlendOp = (byte)BlendOperation.AC_SRC_OVER;
blendFunction.BlendFlags = (byte)BlendFlags.Zero;
blendFunction.SourceConstantAlpha = transp;
blendFunction.AlphaFormat = (byte)0;
PlatformAPIs.AlphaBlend(hdcDst, x, y, image.Width, image.Height, hdcSrc,
0, 0, image.Width, image.Height, blendFunction);
Initalize the image
I have loaded all the images of the Form in the constructor of the class on the OnPaint(), firtly I positioned the images that do not have interaction and, in the end, I added the buttons that require interaction.
Sample of constructor
path = System.IO.Path.GetDirectoryName(Assembly.GetExecutingAssembly().GetName().CodeBase);
backImage = new Bitmap(path + @"\BMP\wallpaper.bmp");
topBar = new Bitmap(path + @"\BMP\topbar.bmp");
topLock = new Bitmap(path + @"\BMP\toplock.bmp");
Drawing all the images
Sample of drawing (OnPaint)
DrawAlpha(gxBuffer, signal, 200, 0, 0);
DrawAlpha(gxBuffer, topLock, 200, signal.Width, 0);
DrawAlpha(gxBuffer, GetBatteryImage(), 200, topLock.Width + signal.Width, 0);
The screen isn't static'. The battery image changes when the SO changes this registry key. To do this I used the notification broker and split the image in more several parts and added a more comprehensive step.
I also added a method that decides which image is the right to see (of course, this is used in the OnPaint())
private Bitmap GetBatteryImage()
_HideBattery = !_HideBattery;
Battery animation sample
GSM signal strenght
Same thing for the GPS signal.
private Bitmap GetGPSSignalImage()
int SignalStrength = SystemState.PhoneSignalStrength;
if (SignalStrength > 80)
if (SignalStrength > 60)
if (SignalStrength > 50)
if (SignalStrength > 20)
_HideSignal = !_HideSignal;
Signal animation sample
Info: WM 6 emulators must be connected to the Fake Network through Cellular Emulator. Below I add some steps that may be useful.
Running Cellular Emulator
- Launch the Cellular Emulator (Start/All Programs / Windows Mobile 6 SDK / Tools / Cellular Emulator ) and the Device Emulator.
- Read the COM port configuration from the status bar of the Cellular Emulator main window.
- In the Device Emulator, go to File / Configure and select the Peripherals tab.
- Map the Serial port 0 of Device Emulator to the specific COM number obtained from step 2
- Soft reset the Device Emulator (File / Reset / Soft).
Drawing the animated slide
In the end of the form I added another animation but the image does not change along with the system situation.
As this is an animation, I chose to load everything onto a single image and added all the frames that are necessary for displaying it. <immagini>
<immagini>In order to create the animation I move the area to view. In other words, only the frame that is necessary in that exact moment is displayed.
Drawing the time
I added a timer that regularly checks the time and updates it on the display.
private void DrawDateAndTime(string time, Graphics gx, int y)
SizeF sizeTime = gx.MeasureString(time, timeFont);
int xTime = this.Width / 2 - (int)sizeTime.Width / 2;
gx.DrawString(time, timeFont, new SolidBrush(Color.White), xTime, y);
SizeF sizeDate = gxBuffer.MeasureString(date, dateFont);
int xDate = this.Width / 2 - (int)sizeDate.Width / 2;
gxBuffer.DrawString(date, dateFont, whiteBrush, xDate, 70);
<immagini>This is the view with the windows clock.
Draw the button
All my button not need the transparency and i've create
ImageButton.cs a class for its.
ImageButtonhave two bitmaps<immagini><immagini>
it overrides the,<immagini><immagini>
and draw it selfs in the <immagini><immagini>
public void Paint(Graphics gx)
ImageAttributes attrib = new ImageAttributes();
Color color = GetTransparentColor(image);
if (!pushed || imageDown == null)
gx.DrawImage(image, clientArea, 0, 0, clientArea.Width, clientArea.Height,
gx.DrawImage(imageDown, clientArea, 0, 0, clientArea.Width, clientArea.Height,
The transparency colour is set based on the first pixel of the image.
private Color GetTransparentColor(Bitmap image)
return image.GetPixel(0, 0);
<immagini><immagini>This is a sample of the button images. <immagini>
Moving the button
In order to move the arrow button I used the
SlideButton that inherits the previous one and adds functions to the movement. Once the mouse is released, the
owner_MouseUp triggers the timer start with
timeAnimation_Tick hereunder you can see the code.
private void timeAnimation_Tick(object sender, EventArgs e)
int x = (start.X - 20);
void Move(int x)
int shift = x - start.X;
int newX = (this.clientArea.X + shift); if (newX <= leftLimit)
newX = leftLimit;
timeAnimation.Enabled = false;
if (newX + this.clientArea.Width >= rightLimit)
newX = rightLimit - this.clientArea.Width;
unLock = true;
this.clientArea = new Rectangle(newX, clientArea.Y, this.clientArea.Width, this.clientArea.Height);
start.X = x;
The Main menu is displayed when the arrow button gets to the end of the race.
It hides itself when the key button is pressed. <anim2>
Drawing the buttons
All my buttons do not need the transparency. I created ImageButton.cs class for this.
The ImageButton has two bitmaps images and imageDown, it overrides the ,MouseDown, and ,MouseUp, and is drawn in the
In the constructor I loaded all the bitmaps and set the Button GridPosition. The
OnPaint draws all the Buttons.
A timer monitors which button is pressed and closes itself if necessary
private void timerCheckButtonPressed_Tick(object sender, EventArgs e)
IntPtr activeWindowHandle = GetForegroundWindow();
IntPtr thisWindowHandle = this.Handle;
if (activeWindowHandle != thisWindowHandle)
if (DialogResult != DialogResult.OK)
NeedRepaint = true;
NeedRepaint = false;
catch (Exception ex)
CheckButtonPress checks if a button is pressed and executes its command.
private bool CheckButtonPress()
buttonCalendar.IsPressedOneTime = false;
buttonPhoto.IsPressedOneTime = false;
buttonMail.IsPressedOneTime = false;
buttonPhone.IsPressedOneTime = false;
Executing the programs or links
In order to execute the program I created the
ProcessExecute that directly executes the program or the link I need.
Here’s a sample:
public static void Phone()
keybd_event(VK_TTALK, 0, KEYEVENTF_KEYDOWN, 0);
public static void MediaPlayer()
internal static void TaskManager()
public static void Picture()
StartLink(@"\Windows\Start Menu\Programs\Pictures & Videos.lnk");
public static void Camera()
CameraCaptureDialog cameraCapture = new CameraCaptureDialog();
And this is the
public static void StartProcess(string FileName)
System.Diagnostics.Process myProcess = new System.Diagnostics.Process();
myProcess.StartInfo.FileName = FileName;
Info about Task Manager: The
TaskMgr.exe is only available in WM 6.1 or higher. However I search it and I don't show the button if it's not present. As the image below.
Points of Interest
I would like to remind that this program is not a complete interface. It does not really lock the telephone like iPhone does, it does not display the iPhone calendar when calendar is pressed and it does not modify the telephone Home.
I believe I have proved how simple is drawing with transparencies and animations, both using a single image or several.
I also believe that a skilled developer should not take much to make it screen aware and add menus, buttons and animation between the forms of its application.
- 11 Dec 2008 - First release.
- 13 Dec 2008 - Solved bug
after closing an external application.
- 24 Mar 2009 - New minor release v1.1
- Added CameraCaptureDialog
- Added TaskManager (only for WM 6.1 or higher)
- Added Exit button