SetAlpha32

旧ブログからのコード移植、その２。

SetAlpha32　は PixelFormat.Format32bppArgb の元画像のアルファ値を
均一に設定した値に減少させる。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
using ImageUtils;

namespace LuminanceToAlpha
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        public static bool LuminanceToAlpha(Bitmap bmp, bool bStretch,
            Color baseColor, out Bitmap result32)
        {
            result32 = null;

            if (bmp.PixelFormat != PixelFormat.Format24bppRgb)
                return false;

            int w = bmp.Width;
            int h = bmp.Height;

            Bitmap bw = bmp.Clone() as Bitmap;
            ImgUtils.GrayScale(ref bw);
            if (bStretch) ImgUtils.HistoStretch(ref bw);

            result32 = new Bitmap(w, h, PixelFormat.Format32bppArgb);

            Graphics g = Graphics.FromImage(result32);
            g.Clear(baseColor);
            g.Dispose();

            BmpProc8 src = new BmpProc8(bw);
            BmpProc32 dst = new BmpProc32(result32);

            for (int y = 0; y < h; y++)
                for (int x = 0; x < w; x++)
                {
                    dst[x, y, eRGB.a] = (byte)(255 - src[x, y]);
                }
            ImgUtils.CallDispose(dst, src, bw);

            return true;
        }

        public static bool SetAlpha32(ref Bitmap bmp, int percent)
        {
            if (bmp.PixelFormat != PixelFormat.Format32bppArgb)
                return false;

            int w = bmp.Width;
            int h = bmp.Height;

            double p = percent / 100d;

            BmpProc32 dst = new BmpProc32(bmp);

            for (int y = 0; y < h; y++)
                for (int x = 0; x < w; x++)
                {
                    if (dst[x, y, eRGB.a] == 0) continue;
                    dst[x, y, eRGB.a] = ImgUtils.AdjustByte(dst[x, y, eRGB.a] * p);
                }
            dst.Dispose();

            return true;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Bitmap bmp = new Bitmap(@"c:\Home\ImgWork\SASample2.png");

            int w = bmp.Width;
            int h = bmp.Height;

            Bitmap tmp1, tmp2;
            Color baseColor = Color.FromArgb(10, 00, 70);

            LuminanceToAlpha(bmp, true, baseColor, out tmp1);


            Graphics g = this.CreateGraphics();

            for (int i = 0; i < 5; i++)
            {
                tmp2 = tmp1.Clone() as Bitmap;
                SetAlpha32(ref tmp2, 15 + 20 * i);
                g.DrawImage(tmp2, 20 + 150 * i, 50 + 30 * i, w, h);
                tmp2.Dispose();
            }

            g.Dispose();

            tmp1.Dispose();
            bmp.Dispose();
        }
    }
}