c# - 在 .NET 中提取图像的一部分

Question

我有一张卡片的 PNG 作为 1 张图像（它将所有 52 张卡片组合成 1 个图像文件）。如何根据需要提取单个卡（或在启动时将它们全部提取到单独的图像文件中）。

我了解知道要获取哪一行和哪一列的逻辑，它是我遇到问题的实际图像处理代码。

我正在使用 Visual Studio 2010 和 VB（尽管任何 .NET 语言的示例代码都可以）。

我不允许发布图像本身，但这是一个示例图像

http://www.jfitz.com/cards/windows-playing-cards.png

谢谢。

Answer 1

这将加载原件并创建一个从 (0,0) 开始且尺寸为 100x100 的裁剪版本。您必须编写逻辑来迭代每张卡片，知道何时移动到下一行等。但是，一旦您知道坐标和尺寸，这应该有助于您取出卡片。

Bitmap cards = new Bitmap(@"C:\SomePath\");
Rectangle srcRect = new Rectangle(0, 0, 100, 100);
Bitmap card = (Bitmap)cards.Clone(srcRect, cards.PixelFormat);

顺便说一句，我没有包括对 card.Save() 的调用，因为在保存期间有很多选项需要设置，这有点超出了你的问题范围。但是，有关如何将其保存到磁盘的信息，请参阅 http://msdn.microsoft.com/en-us/library/ytz20d80.aspx。

Answer 2

我非常无聊，看看这是否有帮助。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;

namespace CardDeck
{
    public class CardCropper
    {
        private Bitmap _source;
        private int _cardsPerRow;
        private int _rowCount;
        private int _cardCount;
        private int _cardWidth;
        private int _cardHeight;

        public CardCropper(Bitmap source, int rowCount, int cardsPerRow)
        {
            _source = source;
            _cardsPerRow = cardsPerRow;
            _rowCount = rowCount;
            _cardCount = _cardsPerRow * _rowCount;
            _cardWidth = source.Width / _cardsPerRow;
            _cardHeight = source.Height / _rowCount;
        }

        public Bitmap[,] CropCards()
        {
            var cards = new Bitmap[_rowCount, _cardsPerRow];

            for (int y = 0; y < _rowCount; y++)
            {
                for (int x = 0; x < _cardsPerRow; x++)
                {
                    cards[y, x] = CropCard(x, y);
                }
            }

            return cards;
        }

        private Bitmap CropCard(int x, int y)
        {
            var rect = new Rectangle(x * _cardWidth, y * _cardHeight, _cardWidth, _cardHeight);

            return _source.Clone(rect, _source.PixelFormat);
        }
    }

    public class CardDeck
    {
        private int _limit;
        private int _cardsPerRow;
        private int _index = 0;
        private Bitmap[,] _cards;

        public int Index
        {
            get
            {
                CheckLimits();
                return _index;
            }
            set
            {
                _index = value;
                CheckLimits();
            }
        }

        public CardDeck(Bitmap[,] cards, int rowCount, int cardsPerRow)
        {
            _cards = cards;
            _limit = rowCount * cardsPerRow;
            _cardsPerRow = cardsPerRow;            
        }


        public Image GetCardFromIndex()
        {
            var point = GetPointFromIndex();

            return _cards[point.Y, point.X];
        }

        private void CheckLimits()
        {
            if (_index >= _limit)
            {
                _index = 0;
            }

            if (_index < 0)
            {
                _index = _limit - 1;
            }
        }

        private Point GetPointFromIndex()
        {
            int x = this.Index % _cardsPerRow;
            int y = this.Index / _cardsPerRow;

            return new Point(x, y);
        }
    }
}

用法：

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

namespace CardDeck
{
    public partial class CardDeckForm : Form
    {
        private CardDeck _cardDeck = null;

        public CardDeckForm()
        {
            InitializeComponent();

            LoadCards();

            ShowImage();
        }

        private void LoadCards()
        {
            using (var source = new Bitmap(@"AllCards.png"))
            {
                var cards = new CardCropper(source, rowCount: 4, cardsPerRow: 13).CropCards();
                _cardDeck = new CardDeck(cards, rowCount: 4, cardsPerRow : 13);
            }
        }

        private void NextButton_Click(object sender, EventArgs e)
        {
            _cardDeck.Index++;
            ShowImage();
        }

        private void PreviousButton_Click(object sender, EventArgs e)
        {
            _cardDeck.Index--;
            ShowImage();
        }

        private void ShowImage()
        {
            this.cardPictureBox.Image = _cardDeck.GetCardFromIndex();
        }
    }
}

Answer 3

public static System.Drawing.Image CropBitmap(Bitmap bitmap, int cropX, int cropY, int cropWidth, int cropHeight)
        {
            System.Drawing.Rectangle rect = new System.Drawing.Rectangle(cropX, cropY, cropWidth, cropHeight);
            System.Drawing.Image cropped = bitmap.Clone(rect, bitmap.PixelFormat);
            return cropped;
        }