GDI + Tổng quan Trong khi Windows Forms cung cấp một cơ sở tuyệt vời cho phần lớn các giao diện người dùng,. NET Framework cho phép truy cập đến khả năng dựng hình đầy đủ của Windows XP. Hầu hết GDI + làm việc cũng sẽ liên quan đến việc viết mã đầu vào tùy chỉnh. | int id instanceCounter internal TwoState State hndlr new buttonClick hndlr bool state true public string State get return state true On Off set state value On true false OnStateChanged private void buttonClick object sender e changeState public void changeState state state OnStateChanged public void OnStateChanged TwoState id id state changed State class ChristmasTree Panel bool allOn internal bool AllOn get return allOn 574 Thinking in C public ChristmasTree TwoState ts new TwoState new Point 10 10 TwoState ts2 new TwoState new Point 120 10 Add ts Add ts2 BackColor public void Add TwoState c c new EventHandler public void AddRange TwoState ca foreach TwoState ts in ca new EventHandler ca public void TwoClickChanged Object src EventArgs a allOn true foreach Control c in Controls TwoState ts c as TwoState if On allOn false if allOn BackColor else BackColor Chapter 14 Programming Windows Forms 575 class PACForm Form ChristmasTree pl new ChristmasTree ChristmasTree p2 new ChristmasTree public PACForm ClientSize new Size 450 200 Text Events Models new Point l0 l0 new Point 200 l0 pl p2 static void Main new PACForm When run if you set both the buttons within an individual ChristmasTree panel to On the ChristmasTree s background color will become green otherwise the background color will be red. The PACForm knows nothing about the TwoStates within the ChristmasTree. We could and indeed it would probably be logical change TwoState from descending from Button to descending from Checkbox and from a string to a bool and it would make no difference to the PACForm that contains the two instances of ChristmasTree. .
