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Articles 3D Audio Custom Controls General RB Graphics Hacks Mac OS X Menus Novelty Printing REALbasic 2005 REALbasic 2006 Registration Resources Reviews Serial Speech Sockets XML Video Resource Links News Current News February 2006 January 2006 December 2005 November 2005 October 2005 September 2005 August 2005 July 2005 June 2005 May 2005 April 2005 March 2005  REALbasic for Dummies by Erick Tejkowski  Learning REALbasic through Applications REALbasic for Macintosh REALbasic Cross-Platform Application Development 
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If you've used a Mac for any time at all, you have no doubt stumbled across the various screenshot keyboard shortcuts available in Mac OS 8/9. Mac OS X users have a special treat in the "Grab.app" application that accompanies a default installation. This week we'll create a simple screenshot application . Our version will be different, because it has a moveable viewer. What good is a moveable viewer? It allows you to take screenshots of the same exact area and size each time. Doing the same thing with other screenshot tools is tedious if not impossible. By the end of this week's project, you should know how to use plugins and irregularly shaped windows in your REALbasic project. Preparation This week's tutorial makes use of two different plugins:
Before you begin this tutorial, download both of these plugins and place them in the REALbasic "Plugins" folder. Joe's plugin takes care of snapping the screenshot for us. Michio's plugin provides us the opportunity to create irregularly-shaped windows. The idea behind this project is that we will draw a see through ring on the screen. Then, whenever a user selects Save, whatever appears within the ring will be saved on the desktop as a JPEG image (thanks to Joe's plugin). In reality, the ring will just be a window that has a transparent center and no other common window features. Michio's plugin lets you create windows that look like anything but a window. For our example, we'll create a window that looks like a red ring. Building the Project Launch REALbasic and double click Window1 to open its Window Editor. Change the properties of Window1 to match those in the following image: 
Add an EditField control to Window1 and set its LimitText property to 1. Why the EditField? We'll hide it from view and use it to capture keystrokes of the number keys 1-6. This will give us the chance to let users alter the size of the screen capture ring. For now, you can place EditField1 anywhere in the window. By now, your interface should look like this: 
Next, close Window1 and open the Menu Editor. Add a new menu item to the File Menu like so: 
Close the Menu Editor and select File->New Class. Change the properties for this class to match the following image: 
The final step before you can start coding is to add a sound file to the project. Peek inside the System suitcase with ResEdit if you really like the Finder's Cmd-Shift-3 camera sound. When you've decided on a sound, drag it into the project window. Adding the Code The code for this project is contained in two places: in Window1 and the App class. The Window code is based on the code provided with Michio Ono's plugin. It takes care of drawing the window with a transparent center and also manages the redrawing of it. The code within the application class does the task of taking the screenshot and saving it as a JPEG file. To start, open Window1 and double-click it again to open its Window Editor. By selecting Edit->New Property, create the following three Window1 properties:
Next, create a new method (Edit->New Method) and define it as :DrawCaptureRing Finally, fill in the code for each element in this code listing: Window1.DrawCaptureRing:Sub DrawCaptureRing() //Erase the last ring ringPicture.Graphics.ForeColor = RGB( 255,255,255 ) ringPicture.Graphics.FillRect 0,0,screen(0).width,screen(0).height //Draw the new ring ringPicture.Graphics.ForeColor = RGB( 0,0,0 ) ringPicture.Graphics.penwidth=10 ringPicture.Graphics.penheight=10 ringPicture.Graphics.DrawRect 0,0,me.width,me.height Hide MicSetWindowRegion ringPicture Show Visible = True //capture any new keystrokes editfield1.text="" editfield1.setfocus End Sub Window1.MouseDown: Function MouseDown(X As Integer, Y As Integer) As Boolean ringX = X ringY = Y return true End Function Window1.Paint: Sub Paint(g As Graphics) //Redraw the window if Self.Visible then DrawCaptureRing(FALSE) end if End Sub Window1.MouseDrag: Sub MouseDrag(X As Integer, Y As Integer) Dim newLeft, newTop As Integer if ringX <> X or ringY <> Y then newLeft = (X-ringX) newTop = (Y-ringY) Left = Left + newLeft Top = Top + newTop end if End Sub Window1.Open: Sub Open() //Create a new picture to store the screenshot ringPicture = NewPicture( screen(0).width, screen(0).height, 32 ) //Init the window Show Visible = true self.refresh editField1.top=-100 editField1.setfocus End Sub Window1.EditField1.KeyDown: Function KeyDown(Key As String) As Boolean //this checks for keypresses //on the 1-6 keys //to change the size of the "capture ring" select case key case "1" if self.width<>100 then DrawCaptureRing self.width=100 self.height=100 DrawCaptureRing end if case "2" if self.width<>200 then DrawCaptureRing self.width=200 self.height=200 DrawCaptureRing end case "3" if self.width<>300 then DrawCaptureRing self.width=300 self.height=300 DrawCaptureRing end case "4" if self.width<>400 then DrawCaptureRing self.width=400 self.height=400 DrawCaptureRing end case "5" if self.width<>500 then DrawCaptureRing self.width=500 self.height=500 DrawCaptureRing end case "6" //fullscreen if self.width<>screen(0).width then DrawCaptureRing self.width=screen(0).width-10 self.height=screen(0).height-10 self.left=0 DrawCaptureRing end end select return true End Function Once you have all the code entered for Window1, open the App subclass and add this code to the EnableMenuItems event: app.EnableMenuItems:Sub EnableMenuItems() FileCaptureScreen.enabled = true End Sub Select Edit->New Menu Handler and choose the FileCaptureScreen menu that you created earlier. Add the following code to it: dim p as picturedim f as folderItem dim thefilename as string dim d as date d = new date thefilename = d.longtime+".jpg" //we can't have a ":" in a file name, so replace it with a dash thefilename = replaceAll(thefilename,":","-") //capture the screen within the frame p = CaptureScreen(Window1.left+10, Window1.top+10,Window1.width-10, Window1.height-10) f=DesktopFolder.child(thefilename) if f<>nil then if p<>nil then //save the picture as a JPEG CaptureSound.play f.saveAsJpeg(p) end if end if Conclusion If all of this code has you nervous, you can download the completed project. When you have a working copy of the project, you should be able to resize the screenshot area by pressing one of the numbers keys (1-6). Pressing Cmd-S should place the screenshot on the desktop with a filename displaying the time it was created. Keep in mind that this application only works with Mac OS 8/9/Classic. This is due to the fact that neither Joe's nor Michio's plugin support Carbon. Until next week, happy shooting! |
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