我一直在开发一个小应用程序，可以让用户将图像转换为不同的尺寸和格式。但我一直在努力设计这个应用程序。虽然我已经让应用程序运行起来了，但它并没有很好地集成面向对象的设计。由于这是一个个人项目，我一直想学习更多关于接口集成、良好的类继承、对象组合以及其他面向对象设计元素的知识。
然而，我一直在努力实现这些。别误会，我知道什么是面向对象设计以及它的原理，只是我不知道如何在项目中实现良好的面向对象设计。当然，看书或在线阅读类示例很容易。例如下面这个简单的场景：
接口 IPerson 有成员函数 Walk() 和 Run()。抽象类 Person 使用 IPerson 接口。类 Man 和类 Female 继承自抽象类 Person。
但是，当涉及到真正的项目时，我很难实现良好的设计。我希望能得到一些见解。以下是我目前拥有的接口：
然而，我一直在努力实现这些。别误会，我知道什么是面向对象设计以及它的原理，只是我不知道如何在项目中实现良好的面向对象设计。当然，看书或在线阅读类示例很容易。例如下面这个简单的场景：
接口 IPerson 有成员函数 Walk() 和 Run()。抽象类 Person 使用 IPerson 接口。类 Man 和类 Female 继承自抽象类 Person。
但是，当涉及到真正的项目时，我很难实现良好的设计。我希望能得到一些见解。以下是我目前拥有的接口：
interface IPicture
{
Bitmap ReturnImage(string path, int width, int height);
}
主要的类，用于保存图片相关信息。该类基本上存储有关传递的图像的信息以及用户想要的新值的信息（例如新大小、新文件位置、新图片格式等）。
public class MyPictures : IPicture
{
//All Private variables below are properties. Property get/set's have been removed
//for the sake of space
private int _NewWidth;
private int _NewHeight;
private string _NewImgName;
private string _NewImgPath;
private string _NewImgFullPath;
private ImageFormat _NewImgFormat;
//Declare variables to hold values that have been determined
private int _OldWidth;
private int _OldHeight;
private string _OldImgName;
private string _OldImgPath;
//Old Image Format is in String format because of certain extension scenarios.
private string _OldImgFormat;
public MyPictures(Image img, string file)
{
ClearProperties();
//...set properties based on passed variables in constructor...
}
public void ClearProperties()
{
_NewWidth = 0;
_NewHeight = 0;
_NewImgName = "";
_NewImgPath = "";
_NewImgFullPath = "";
_NewImgFormat = null;
_OldWidth = 0;
_OldHeight = 0;
_OldImgName = "";
_OldImgPath = "";
_OldImgFormat = null;
}
public override string ToString()
{
return _OldImgPath;
}
public void ImageSave()
{
Bitmap tempBmp = new Bitmap(_OldImgPath);
Bitmap bmp = new Bitmap(tempBmp, _NewWidth, _NewHeight);
bmp.Save(_NewImgPath + @"\" + _NewImgName + "." + _NewImgFormat.ToString().ToLower(), _NewImgFormat);
}
public Bitmap ImageClone()
{
Bitmap bmp = new Bitmap(_OldImgPath);
return bmp;
}
Bitmap IPicture.ReturnImage(string path, int width, int height)
{
return new Bitmap(new Bitmap(path), width, height);
}
}
主类; 应用程序的起始点。这肯定需要一些工作...
public partial class Form1 : Form
{
static bool hasThreadBeenStopped = false;
static bool imageProcessingComplete = false;
static bool imgConstrained = false;
//Default text when user selects 'All' checkbox for new image name
static string newNameDefault = "'Name' + #";
Utility.Validation.Validate valid = new Utility.Validation.Validate();
public Form1()
{
InitializeComponent();
//Populate Combo Box With Possible Image Formats...
//Conditionally show Image Properties...
ImgPropertiesEnabled();
//Set static progress bar properties...
progressBar1.Minimum = 0;
progressBar1.Step = 1;
}
private void Form1_Load(object sender, EventArgs e)
{
lblImgProcessed.Text = "";
lblFile.Text = "";
txtContentFolder.Text = "";
}
//Delegate declarations. Used for multi-thread processing
public delegate void PopulateTextboxDelegate(Label lbl, string text);
public delegate void ThreadWorkDelegate(Label lbl, string text);
public delegate void ImageDisplayDelegate(Image i);
public delegate void ProgressBarDelegate(ProgressBar p, int step, int value);
//Populate textbox fields with image processed, and image path being processed
public void PopulateTextbox(Label lbl, string text)
{
lbl.Text = "";
lbl.Text = text;
}
public void ThreadWork(Label lbl, string text)
{
this.Invoke(new PopulateTextboxDelegate(PopulateTextbox),
new object[] { lbl, text });
}
//Display Currently Processed Image
public void ImageDisplay(Image i)
{
pbMain.Image = null;
pbMain.Image = i;
}
public void ThreadWorkImg(Image i)
{
this.Invoke(new ImageDisplayDelegate(ImageDisplay),
new object[] {i});
}
//Increment Progress Bar
public void ProgressBarDisplay(ProgressBar pg, int max, int value)
{
//Dynamically set the Progress Bar properties
pg.Maximum = max;
pg.Value = value;
}
public void ThreadProgress(ProgressBar p, int max, int value)
{
this.Invoke(new ProgressBarDelegate(ProgressBarDisplay),
new object[] { p, max, value });
}
private void btnStart_Click(object sender, EventArgs e)
{
string IsValidResult = IsValid();
//If string is empty, Utility passed
if (IsValidResult == "")
{
Thread t = new Thread(new ThreadStart(ProcessFiles));
t.Start();
}
else
{
MessageBox.Show(IsValidResult);
}
}
public void ProcessFiles()
{
int count = 0;
ThreadWorkDelegate w = ThreadWork;
ImageDisplayDelegate im = ThreadWorkImg;
ProgressBarDelegate pb = ThreadProgress;
try
{
foreach (MyPictures mp in lstHold.Items)
{
try
{
if (hasThreadBeenStopped == false)
{
//Disable certain controls during process. We will use the generic
//MethodInvoker, which Represents a delegate that can execute any method
//in managed code that is declared void and takes no parameters.
//Using the MethodInvoker is good when simple delegates are needed. Ironically,
//this way of multi-thread delegation was used because the traditional way as used
//by the rest of the delegates in this method, was not working.
btnApply.Invoke(new MethodInvoker(delegate { btnApply.Enabled = false; }));
btnStart.Invoke(new MethodInvoker(delegate { btnStart.Enabled = false; }));
//Call delegate to show current picture being processed
im.BeginInvoke(mp.ImageClone(), null, null);
mp.ImageSave();
//Increment Count; Image has been processed
count++;
//Invoke Img Proceessed Output
w.BeginInvoke(lblImgProcessed, count.ToString() +
" of " + lstHold.Items.Count.ToString() + " processed",
null, null);
//Invoke File Process Output
w.BeginInvoke(lblFile, mp.NewImgPath, null, null);
//Invoke Progressbar output. Delegate is passed The count of images,
//which will be set as the progressbar max value. the 'count' variable is
//passed to determine the current value.
pb.BeginInvoke(progressBar1, lstHold.Items.Count, count, null, null);
}
else //Thread has been called to stop
{
MessageBox.Show("Image Processing Stopped: " + count + "of " +
lstHold.Items.Count + " processed");
//Enable controls after process
btnApply.Invoke(new MethodInvoker(delegate { btnApply.Enabled = true; }));
btnStart.Invoke(new MethodInvoker(delegate { btnStart.Enabled = true; }));
break;
}
}
catch (Exception ex)
{
MessageBox.Show("Error while processing pictures");
break;
}
}
}
catch (Exception ex)
{
MessageBox.Show("Error while attempting to execute pictures: " + ex.ToString());
}
finally
{
//Loop has ended:
//In finally statement, re-enable disabled controls
//Enable certain controls during process
btnApply.Invoke(new MethodInvoker(delegate { btnApply.Enabled = true; }));
btnStart.Invoke(new MethodInvoker(delegate { btnStart.Enabled = true; }));
//Reset class variables
hasThreadBeenStopped = false;
imageProcessingComplete = false;
}
}
private void btnContent_Click(object sender, EventArgs e)
{
string selection = null;
string[] files = null;
lstAll.Items.Clear();
contentBrowser.ShowDialog();
selection = contentBrowser.SelectedPath;
txtContentFolder.Text = selection;
if (selection != "" || selection != null)
{
try
{
files = System.IO.Directory.GetFiles(selection.Trim());
foreach (string file in files)
{
lstAll.Items.Add(file);
}
}
catch (Exception ex)
{
// MessageBox.Show(ex.ToString());
}
}
}
private void btnGo_Click(object sender, EventArgs e)
{
//Grab files from folder based on user input in the textbox.
string selection = txtContentFolder.Text.Trim();
string[] files = null;
lstAll.Items.Clear();
if (valid.IsNull(selection) == false || valid.IsEmpty(selection) == false)
{
try
{
files = System.IO.Directory.GetFiles(selection);
foreach (string file in files)
{
lstAll.Items.Add(file);
}
}
catch (Exception ex)
{
MessageBox.Show("Invalid Directory");
}
}
txtContentFolder.Text = selection;
}
private void btnDestination_Click(object sender, EventArgs e)
{
string selection = null;
destinationBrowser.ShowDialog();
selection = destinationBrowser.SelectedPath;
txtNewImgPath.Text = selection;
}
private void exitToolStripMenuItem_Click(object sender, EventArgs e)
{
this.Close();
}
private void btnStop_Click(object sender, EventArgs e)
{
//Flag variable that the stop button has been called. This variable is checked
//conditionally when looping over each picture.
hasThreadBeenStopped = true;
}
public string IsValid()
{
StringBuilder sb = new StringBuilder("");
if (lstHold.Items.Count <= 0)
{
return "No items exist to process";
}
//Validate that there is a value in each field for every object in lstHold. All the fields will be
//validated. Note: If there is one invalid field, the rest do not need to be considered.
foreach (MyPictures mp in lstHold.Items)
{
if (mp.NewImgName == "")
{
sb.Append(mp.OldImgPath + ", ");
}
else if (mp.NewImgPath == "")
{
sb.Append(mp.OldImgPath + ", ");
}
else if (mp.NewImgFormat == null)
{
sb.Append(mp.OldImgPath + ", ");
}
else if (mp.NewWidth == 0)
{
sb.Append(mp.OldImgPath + ", ");
}
else if (mp.NewHeight == 0)
{
sb.Append(mp.OldImgPath + ", ");
}
}
//If the returned string is empty, the image is valid. The check for the listbox's count
//will return a string immediatly if false. Because of this, we know that the returning
//string at this level will either be empty (validation passed) or filled with image paths
//of images missing required values. If image is not valid, return this concatenated string of image paths
//that are missing values, and insert a prefixed string literal to this list.
if (sb.ToString() != "")
{
sb.Insert(0, "The following images are missing required values: ");
return sb.ToString();
}
else //String is empty and has passed validation
{
return sb.ToString();
}
}
private void btnMoveOne_Click(object sender, EventArgs e)
{
//Loop through All strings in the lstAll list box. Then use each picture path to convert
//each picture into their own class
foreach (string file in lstAll.SelectedItems)
{
//isImgExistFlag is a flag indicating wheter the image coming from lstAll already exists
//in lstHold. By default, the variable is false. It is set to true if an image does exist
//This variable must be re-created within the scope of the main foreach loop to ensure a proper
//reset of the variable for each image comparison.
bool isImgExistFlag = false;
try
{
Image img;
img = Image.FromFile(file);
MyPictures mp = new MyPictures(img,file);
//If lstHold contains no items, add the item with no validation check.
if (lstHold.Items.Count == 0)
{
lstHold.Items.Add(mp);
}
else
{
//Run through each object in the lstHold to determine if the newly created object
//already exists in list box lstHold.
for (int i = 0; i < lstHold.Items.Count; i++)
{
MyPictures p = (MyPictures)lstHold.Items[i];
//Unique objects will be identified by their Original Image Path, because
//this value will be unique
if (p.OldImgPath == mp.OldImgPath)
{
isImgExistFlag = true;
}
}
//If isImgExistFlag is false, the current Image object doesnt currently exist
//in list box. Therefore, add it to the list.
if (isImgExistFlag == false)
{
lstHold.Items.Add(mp);
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
}
private void btnMoveAll_Click(object sender, EventArgs e)
{
//This event has the same functionality as btnMoveOne_Click, except the main foreach loop
//is based on all of lstAll's items, rather than just the selected items.
foreach (string file in lstAll.Items)
{
bool isImgExistFlag = false;
try
{
Image img;
img = Image.FromFile(file);
MyPictures mp = new MyPictures(img, file);
if (lstHold.Items.Count == 0)
{
lstHold.Items.Add(mp);
}
else
{
for (int i = 0; i < lstHold.Items.Count; i++)
{
MyPictures p = (MyPictures)lstHold.Items[i];
if (p.OldImgPath == mp.OldImgPath)
{
isImgExistFlag = true;
}
}
if (isImgExistFlag == false)
{
lstHold.Items.Add(mp);
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
}
private void btnRemoveOne_Click(object sender, EventArgs e)
{
/*
Create a seperate List to populate:
This is necessary because if you explicitly remove an item from the listbox
you will get the following error:
"List that this enumerator is bound to has been modified. An enumerator can
only be used if the list does not change."
*/
//This variable will keep track of the first index processed.
int first_index = 0;
int count = 0;
List<MyPictures> TempMp = new List<MyPictures>();
if (lstHold.Items.Count >= 1)
{
try
{
foreach (MyPictures mp in lstHold.SelectedItems)
{
if (count == 0)
{
first_index = lstHold.SelectedIndex;
}
//Add objects to be removed
TempMp.Add(mp);
}
foreach (MyPictures mp2 in TempMp)
{
lstHold.Items.Remove(mp2);
}
}
catch (Exception ex)
{
//Hide Error: MessageBox.Show(ex.ToString());
}
//Select new item in list if possible, as long as there is a item in the list
if (lstHold.Items.Count >= 1)
{
//If the first_index variable = the amount of items in the list, the new selected index
//should be the first index -1. This is because the variable first_index would be the
//index of the now deleted item in the list. Therefore we must subtract the variable by 1
//before assigning it to the selected value. Otherwise, we'll be assigning a selected index that
//no longer exists.
//There is also a check to make sure there is more than one item in the list. Otherwise, we could
//potentially assign a selected index of -1.
if (first_index == lstHold.Items.Count && lstHold.Items.Count != 1)
{
lstHold.SelectedIndex = first_index - 1;
}
else if (lstHold.Items.Count == 1)
{
lstHold.SelectedIndex = 0;
}
else
{
lstHold.SelectedIndex = first_index;
}
}
else
{
ClearTextBoxes();
}
}
}
private void btnRemoveAll_Click(object sender, EventArgs e)
{
lstHold.Items.Clear();
ClearTextBoxes();
ImgPropertiesEnabled();
}
private void lstHold_SelectedIndexChanged(object sender, EventArgs e)
{
//This prevents trying to access a negative index. This can happen when a item is removed.
if (lstHold.SelectedIndex >= 0)
{
try
{
MyPictures mp = (MyPictures)lstHold.Items[lstHold.SelectedIndex];
txtOldName.Text = mp.OldImgName;
txtOldImgPath.Text = mp.OldImgPath;
txtOldImgFormat.Text = mp.OldImgFormat.ToString();
txtOldWidth.Text = mp.OldWidth.ToString();
txtOldHeight.Text = mp.OldHeight.ToString();
txtNewName.Text = mp.NewImgName;
cbFormat.SelectedItem = mp.NewImgFormat;
txtNewWidth.Text = mp.NewWidth.ToString();
txtNewHeight.Text = mp.NewHeight.ToString();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
//Call function to determine which controls should be enabled/disabled
ImgPropertiesEnabled();
}
private void btnApply_Click(object sender, EventArgs e)
{
//Reset color. It could be grey depending on if user changed default name.
txtNewName.ForeColor = Color.Black;
if (lstHold.SelectedIndex == -1)
{
MessageBox.Show("Picture not selected. Select picture to apply properties to.");
}
else if (lstHold.SelectedIndex >= 0)
{
MyPictures mp = (MyPictures)lstHold.Items[lstHold.SelectedIndex];
//User wants to apply a generated name to all pictures within the list
if (chkNewPicName.Checked == true)
{
int count = 0;
foreach (MyPictures pic in lstHold.Items)
{
pic.NewImgName = txtNewName.Text + count.ToString();
++count;
}
txtNewName.Text = mp.NewImgName;
}
//User wants to apply a custom name to this picture only
else
{
mp.NewImgName = txtNewName.Text;
}
//User wants to apply this path to all pictures within the list
if (chkNewPicPath.Checked == true)
{
foreach (MyPictures pic in lstHold.Items)
{
pic.NewImgPath = txtNewImgPath.Text;
}
txtNewImgPath.Text = mp.NewImgPath;
}
//User wants to apply this path to this picture only
else
{
mp.NewImgPath = txtNewImgPath.Text;
}
//User wants to apply this image format to all pictures within the list
if (chkNewPicFormat.Checked == true)
{
foreach (MyPictures pic in lstHold.Items)
{
pic.NewImgFormat = (ImageFormat)cbFormat.SelectedItem;
}
}
//User wants to apply this image format to this picture only
else
{
mp.NewImgFormat = (ImageFormat)cbFormat.SelectedItem;
}
//User wants to apply this size to all pictures
if (chkNewSize.Checked == true)
{
foreach (MyPictures pic in lstHold.Items)
{
pic.NewWidth = Convert.ToInt32(txtNewWidth.Text);
pic.NewHeight = Convert.ToInt32(txtNewHeight.Text);
}
txtNewWidth.Text = mp.NewWidth.ToString();
txtNewHeight.Text = mp.NewHeight.ToString();
}
//User wants to apply this size to this picture only
else
{
mp.NewWidth = Convert.ToInt32(txtNewWidth.Text);
mp.NewHeight = Convert.ToInt32(txtNewHeight.Text);
}
mp.NewImgName = txtNewName.Text;
mp.NewImgFormat = (ImageFormat)cbFormat.SelectedItem;
mp.NewWidth = Convert.ToInt32(txtNewWidth.Text);
mp.NewHeight = Convert.ToInt32(txtNewHeight.Text);
}
}
private void checkBox1_CheckedChanged(object sender, EventArgs e)
{
if (chkSelectAll.Checked)
{
chkNewPicName.Checked = true;
chkNewPicPath.Checked = true;
chkNewPicFormat.Checked = true;
chkNewSize.Checked = true;
}
else
{
chkNewPicName.Checked = false;
chkNewPicPath.Checked = false;
chkNewPicFormat.Checked = false;
chkNewSize.Checked = false;
}
}
private void previewToolStripMenuItem_Click(object sender, EventArgs e)
{
MessageBox.Show("hi there!");
}
private void btnPreview_Click(object sender, EventArgs e)
{
try
{
if (lstHold.Items.Count <= 0)
{
MessageBox.Show("No pictures are available to preview");
}
else if (lstHold.SelectedItem == null)
{
MessageBox.Show("No picture is selected to preview");
}
else
{
MyPictures mp = (MyPictures)lstHold.SelectedItem;
//Bitmap bmp = new Bitmap(mp.OldImgPath);
Form2 frm = new Form2(mp);
frm.Show();
}
}
catch (Exception ex)
{
MessageBox.Show("An Error has occured:\n " + ex.ToString());
}
}
public void ImgPropertiesEnabled()
{
//Enable Image properties when an image is selected
if (lstHold.SelectedIndex >= 0)
{
gbCheckAll.Enabled = true;
gbImgProperties.Enabled = true;
}
else
{
//Disable Image properties when an image is not selected
gbCheckAll.Enabled = false;
gbImgProperties.Enabled = false;
}
//Preview buttons enablement will depend on the same conditions
btnPreview.Enabled = gbImgProperties.Enabled;
}
public void ClearTextBoxes()
{
txtNewImgPath.Text = "";
txtNewName.Text = "";
txtNewHeight.Text = Convert.ToString(0);
txtNewWidth.Text = Convert.ToString(0);
cbFormat.SelectedItem = null;
chkSelectAll.Checked = false;
}
}