260.C# 實作一個簡單的溫度計

摘要

在C# WinForm下開發一個簡單的溫度計控件，主要需要使用到Windows圖形使用者界面(GUI)的技術，并結合了.NET架構的相關技術和Windows作業系統的底層功能，來實作一個直覺、易用的界面和資料處理功能。

正文

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace gdi104
{
    public class TemperatureGauge : Control
    {
        private int minValue = 0;
        private int maxValue = 100;
        private int currentValue = 50;

        public int MinValue
        {
            get { return minValue; }
            set { minValue = value; Invalidate(); }
        }

        public int MaxValue
        {
            get { return maxValue; }
            set { maxValue = value; Invalidate(); }
        }

        public int CurrentValue
        {
            get { return currentValue; }
            set
            {
                if (value < minValue)
                    currentValue = minValue;
                else if (value > maxValue)
                    currentValue = maxValue;
                else
                    currentValue = value;

                Invalidate();
            }
        }

        public TemperatureGauge()
        {
            SetStyle(ControlStyles.ResizeRedraw, true);
            SetStyle(ControlStyles.DoubleBuffer, true);
            SetStyle(ControlStyles.AllPaintingInWmPaint, true);
            SetStyle(ControlStyles.UserPaint, true);

            Width = 60;  // 控制寬度以控制溫度計的高度
            Height = 300; // 控制高度以控制溫度計的寬度
            BackColor = Color.WhiteSmoke;
            Padding = new Padding(2, 20, 2, 20);
         }

        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);

            Graphics g = e.Graphics;
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

            // 繪制背景
            g.FillRectangle(Brushes.White, Padding.Left, Padding.Top, Width - Padding.Horizontal, Height - Padding.Vertical);

            // 繪制邊框
            g.DrawRectangle(Pens.AliceBlue, Padding.Left, Padding.Top, Width - Padding.Horizontal - 1, Height - Padding.Vertical - 1);

            // 繪制刻度線
            for (int i = minValue; i <= maxValue; i += 10)
            {
                float yPos = (float)(maxValue - i) / (maxValue - minValue) * (Height - Padding.Vertical) + Padding.Top;
                g.DrawLine(Pens.Black, Padding.Left + 10, yPos, Padding.Left + 20, yPos);
                g.DrawString(i.ToString(), Font, Brushes.Black, Padding.Left + 25, yPos - 10);
            }

            // 繪制水銀柱
            float indicatorY = (float)(maxValue - currentValue) / (maxValue - minValue) * (Height - Padding.Vertical) + Padding.Top;
            float mercuryHeight = (Height - Padding.Vertical) - (indicatorY - Padding.Top);
            g.FillRectangle(Brushes.Red, Padding.Left + 10, indicatorY, 10, mercuryHeight);
        }
    }
}