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For more tutorial visit www.bukansembarang.info
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w w w . B u k a n S e m b a r a n g . I n f o © 2 0 1 0
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GDI+ : Gradient 2010
w w w . B u k a n S e m b a r a n g . I n f o © 2 0 1 0
GDI+ : Gradient
Learning By Sample Series
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GDI+ : Gradient 2010
Foreword
Learning By Sample ?
So, why should I made this tutorial freely accessed by everyone ? Well, surely I
am just nobody, I also just another ordinary person with ordinary knowledge. However,
I always feel that some persons in the internet giving away their tutorial for free and I
feel being helped by them. Then, I remember one of my senior wisdom words : “If you
want to be given more, then start to give more”. And of course, I really believe those
words, since that I already proof it to be right all the time.
Also, I’m not an English native speaker, however, I just try to improve my
English in any other way, especially in written format. Thus, I think writing is the best
practice to improve my English freely. However, you will find many grammatical errors
in my tutorial, so please send me comments and also suggestion to improve it.
Then, why the format using Learning By Sample series ? Is it really different with
other tutorials out there ? Ehm, I already wrote three books (in Indonesian) using this
kind of format, and many readers already contact me about how this format really help
them to learn from the scratch. So, why in the world I’m not re-create it in English
format, right ? Eventhough actually, it is similar with Hands On Lab series which
already famous in Microsoft site previously.
All of my lesson also being designed as short samples and short time exercise.
Thus, I hope that each of tutorial series would take only at least 10-15 minutes
maximum to learn. Why keep it short ? Because many beginner (and even expert) will
find boring whenever they must keep studying more than 15 minutes (but you will
never get bored when you online in such time right ?).
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Another reason is just because many of samples in this series come up from my
lecturing task exercise. So, I just try to compile all my lab exercises in order to keep it
tidy and also reusable for my students. That’s why you will find many unsorted course
material inside these series, however, just take a seat and enjoy the ride !
Requirements
In this series, I try to give simple example about GDI+. So what is GDI+ anyway ?
GDI+ or GraphicsDrawing Interface is merely part of .NET Framework which entirely
purposed in manipulating graphics. However I’m not going to make you understand
complex theory about this class. I just try to make you understand it in very simple and
stupid way.
All of my samples in this series use Visual Web Developer 2010 Express edition
however you can also do it all using Visual Studio. If you really want to follow this
series, then you should aware that basic programming knowledge is needed. You
should also familiar with ASP .NET especially for version 3.5 above.
FYI, I’m a VB guy, so please don’t complaint if I use VB entirely in this series. But
nowadays, there’s no such useful things if we argue about language differences,
because I just try to share something that I know. So, if you don’t like VB and want to
have another tutorial with your own favourit language, then I’d be happy to read it.
Now, let’s get started…….
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Let’s Get Started
1. First, ensure that you already open Visual Web Developer 2010 Express Edition
2. Create a newly blank website and give it a name
3. Now, let’s create a new blank web page
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4. In newly created web page, insert new table which has 3 rows and 2 columns, by
clicking menu Table � Insert Table and in available dialog box set its rows and
columns value :
5. Then type descriptive text in first and second row at first column
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6. Later put two DropDownList in each rows at second column :
7. Next, put a Button in last row at first column and set its Text property just like this
following picture :
8. Last step in design mode is placing an Image control just right after Button :
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9. Double click at any empty space in Design mode and we should be redirect in to
Page_Load event, and type this codes :
a. First thing first, in this part of code we declare Color enumeration. As you
should know that there are KnownColor enumeration in Color classes at .NET
Framework.
b. Then why we should start it at number 27 ? It just because the first color
until color number 27 merely contains known color from client desktop
theme. It also happen in last 8 known color, thus we do the looping from 27
until last 8 only.
c. And the rest is easy, we just put all the color’s array into available
DropDownList
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10. Now let’s turn again into Code Editor by double clicking the only available Button
and start typing this lines of code :
11. Some typo errors shown ? Don’t worry, just add this line at top of Code Editor :
12. Want some explanations for what the Button do ? Here it go :
a. First, we create the “canvas” for our next gradient brush
b. Next we create the “core” gradient brush with Horizontal Linear mode, you
can also modify it using other mode such as Diagonal or Vertical
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c. In following part, we create a virtual rectangle to hold the gradient sample
d. Afterward, just save it in temporary image file and display it in Image control
e. Of course, never forget to dispose all the object
13. Okay then, let’s execute this web page and see the result :
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14. What do you think ? Too easy ? Well, have fun to try it and we will create another
simple and astonishing sample in next chapter…..