ShareX/ShareX.ScreenCaptureLib/Forms/ScrollingCaptureLightForm.cs

#region License Information (GPL v3)

/*
    ShareX - A program that allows you to take screenshots and share any file type
    Copyright (c) 2007-2023 ShareX Team

    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

    Optionally you can also view the license at <http://www.gnu.org/licenses/>.
*/

#endregion License Information (GPL v3)

using ShareX.HelpersLib;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace ShareX.ScreenCaptureLib
{
    public partial class ScrollingCaptureLightForm : Form
    {
        public ScrollingCaptureOptions Options { get; private set; }
        public Bitmap Result { get; private set; }

        private List<Bitmap> images = new List<Bitmap>();
        private bool isCapturing, scrollTop;
        private int currentScrollCount;
        private WindowInfo selectedWindow;
        private Rectangle selectedRectangle;

        public ScrollingCaptureLightForm(ScrollingCaptureOptions options)
        {
            Options = options;

            InitializeComponent();
            ShareXResources.ApplyTheme(this);

            SelectWindow();
        }

        private void Reset()
        {
            currentScrollCount = 0;

            ResetPictureBox();

            if (images != null)
            {
                foreach (Bitmap bmp in images)
                {
                    bmp?.Dispose();
                }

                images.Clear();
            }

            Result?.Dispose();
        }

        private void ResetPictureBox()
        {
            Image temp = pbOutput.Image;
            pbOutput.Image = null;
            temp?.Dispose();
        }

        private void StartCapture()
        {
            if (!isCapturing)
            {
                isCapturing = true;
                scrollTop = true;
                // TODO: Translate
                btnCapture.Text = "Stop";
                WindowState = FormWindowState.Minimized;
                Reset();
                selectedWindow.Activate();

                tCapture.Interval = Options.StartDelay;
                tCapture.Start();
            }
        }

        private async Task StopCapture()
        {
            if (isCapturing)
            {
                tCapture.Stop();
                // TODO: Translate
                btnCapture.Text = "Capture...";
                btnCapture.Enabled = false;
                this.ForceActivate();

                Result = await CombineImagesAsync(images);
                pbOutput.Image = Result;

                btnCapture.Enabled = true;
                isCapturing = false;
            }
        }

        private bool IsScrollReachedBottom(IntPtr handle)
        {
            SCROLLINFO scrollInfo = new SCROLLINFO();
            scrollInfo.cbSize = (uint)Marshal.SizeOf(scrollInfo);
            scrollInfo.fMask = (uint)(ScrollInfoMask.SIF_RANGE | ScrollInfoMask.SIF_PAGE | ScrollInfoMask.SIF_TRACKPOS);

            if (NativeMethods.GetScrollInfo(handle, (int)SBOrientation.SB_VERT, ref scrollInfo))
            {
                return scrollInfo.nMax == scrollInfo.nTrackPos + scrollInfo.nPage - 1;
            }

            return IsLastTwoImagesSame();
        }

        private bool IsLastTwoImagesSame()
        {
            bool result = false;

            if (images.Count > 1)
            {
                result = ImageHelpers.IsImagesEqual(images[images.Count - 1], images[images.Count - 2]);

                if (result)
                {
                    Bitmap last = images[images.Count - 1];
                    images.Remove(last);
                    last.Dispose();
                }
            }

            return result;
        }

        private void SelectWindow()
        {
            WindowState = FormWindowState.Minimized;
            Thread.Sleep(250);

            if (RegionCaptureTasks.GetRectangleRegion(out selectedRectangle, out selectedWindow, new RegionCaptureOptions()))
            {
                StartCapture();
            }
            else
            {
                this.ForceActivate();
            }
        }

        private async Task<Bitmap> CombineImagesAsync(List<Bitmap> images)
        {
            return await Task.Run(() => CombineImages(images));
        }

        private Bitmap CombineImages(List<Bitmap> images)
        {
            Bitmap result = (Bitmap)images[0].Clone();

            int bestMatchCount = 0;
            int bestMatchIndex = 0;

            for (int i = 1; i < images.Count; i++)
            {
                Bitmap currentImage = images[i];

                int matchCount = 0;
                int matchIndex = 0;
                int matchLimit = currentImage.Height / 3;
                int ignoreSideOffset = Math.Max(50, currentImage.Width / 20);

                if (currentImage.Width < ignoreSideOffset * 3)
                {
                    ignoreSideOffset = 0;
                }

                Rectangle rect = new Rectangle(ignoreSideOffset, result.Height - currentImage.Height, currentImage.Width - ignoreSideOffset * 2, currentImage.Height);

                BitmapData bdResult = result.LockBits(new Rectangle(0, 0, result.Width, result.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
                BitmapData bdCurrentImage = currentImage.LockBits(new Rectangle(0, 0, currentImage.Width, currentImage.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
                int stride = bdResult.Stride;
                int pixelSize = stride / result.Width;
                IntPtr resultScan0 = bdResult.Scan0 + pixelSize * ignoreSideOffset;
                IntPtr currentImageScan0 = bdCurrentImage.Scan0 + pixelSize * ignoreSideOffset;
                int rectBottom = rect.Bottom - 1;
                int compareLength = pixelSize * rect.Width;

                for (int currentImageY = currentImage.Height - 1; currentImageY >= 0 && matchCount < matchLimit; currentImageY--)
                {
                    int currentMatchCount = 0;

                    for (int y = 0; currentImageY - y >= 0 && currentMatchCount < matchLimit; y++)
                    {
                        if (NativeMethods.memcmp(resultScan0 + ((rectBottom - y) * stride), currentImageScan0 + ((currentImageY - y) * stride), compareLength) == 0)
                        {
                            currentMatchCount++;
                        }
                        else
                        {
                            break;
                        }
                    }

                    if (currentMatchCount > matchCount)
                    {
                        matchCount = currentMatchCount;
                        matchIndex = currentImageY;
                    }
                }

                result.UnlockBits(bdResult);
                currentImage.UnlockBits(bdCurrentImage);

                if (matchCount == 0 && bestMatchCount > 0)
                {
                    matchCount = bestMatchCount;
                    matchIndex = bestMatchIndex;
                }

                if (matchCount > 0)
                {
                    if (matchCount > bestMatchCount)
                    {
                        bestMatchCount = matchCount;
                        bestMatchIndex = matchIndex;
                    }

                    Bitmap newResult = new Bitmap(result.Width, result.Height + currentImage.Height - matchIndex - 1);

                    using (Graphics g = Graphics.FromImage(newResult))
                    {
                        g.DrawImage(result, new Rectangle(0, 0, result.Width, result.Height),
                            new Rectangle(0, 0, result.Width, result.Height), GraphicsUnit.Pixel);
                        g.DrawImage(currentImage, new Rectangle(0, result.Height, currentImage.Width, currentImage.Height - matchIndex - 1),
                            new Rectangle(0, matchIndex + 1, currentImage.Width, currentImage.Height - matchIndex - 1), GraphicsUnit.Pixel);
                    }

                    result.Dispose();
                    result = newResult;
                }
            }

            return result;
        }

        private async void btnCapture_Click(object sender, EventArgs e)
        {
            if (isCapturing)
            {
                await StopCapture();
            }
            else
            {
                SelectWindow();
            }
        }

        private void btnOptions_Click(object sender, EventArgs e)
        {

        }

        private async void tCapture_Tick(object sender, EventArgs e)
        {
            if (scrollTop)
            {
                scrollTop = false;
                tCapture.Interval = Options.ScrollDelay;

                InputHelpers.SendKeyPress(VirtualKeyCode.HOME);
                NativeMethods.SendMessage(selectedWindow.Handle, (int)WindowsMessages.VSCROLL, (int)ScrollBarCommands.SB_TOP, 0);

                return;
            }

            Screenshot screenshot = new Screenshot() { CaptureCursor = false };
            Bitmap bmp = screenshot.CaptureRectangle(selectedRectangle);

            if (bmp != null)
            {
                images.Add(bmp);
            }

            if (currentScrollCount == Options.MaximumScrollCount || (Options.AutoDetectScrollEnd && IsScrollReachedBottom(selectedWindow.Handle)))
            {
                await StopCapture();
            }
            else
            {
                InputHelpers.SendMouseWheel(-120 * 2);
                currentScrollCount++;
            }
        }
    }
}