Aspose.PDF for .NET是一種高PDF處理和解析API，用于在跨平臺應(yīng)用程序中執(zhí)行文檔管理和操作任務(wù)。API可以輕松用于生成、修改、轉(zhuǎn)換、渲染、保護和打印PDF文檔，而無需使用Adobe Acrobat。此外，API還提供PDF壓縮選項，表格創(chuàng)建和操作，圖形和圖像功能，廣泛的超鏈接功能，印章和水印任務(wù)，擴展的安全控制和自定義字體處理。

在接下來的系列教程中，將為開發(fā)者帶來Aspose.PDF for .NET的一系列使用教程，例如進行文檔間的轉(zhuǎn)換，如何標記PDF文件，如何使用表單和圖表等等。本文將介紹如何使用圖形，包括：

• 創(chuàng)建填充的矩形對象
• 在圖形對象中添加文本
• 將線對象添加到PDF
• 在頁面上畫線
• 使用Alpha顏色通道創(chuàng)建矩形
• 添加具有透明顏色的圖形
• 控制矩形的Z順序
• 添加帶有漸變填充的圖形

>>Aspose.PDF for .NET更新至最新版v20.7，歡迎下載體驗。

對于使用Adobe Acrobat Writer或其他PDF處理應(yīng)用程序的開發(fā)人員，將圖形添加到PDF文檔是一項非常常見的任務(wù)。PDF應(yīng)用程序中可以使用多種圖形。

Aspose.PDF還支持將圖形添加到PDF文檔。為此，Graph提供了該類。Graph是段落級別的元素，可以Paragraphs在Page實例中添加到集合中。

創(chuàng)建填充的矩形對象

用于.NET的Aspose.PDF支持將圖形對象（例如圖形，線，矩形等）添加到PDF文檔的功能。它還提供了用某種顏色填充矩形對象的功能。

下面的代碼片段顯示了如何添加一個Rectangle充滿顏色的對象。

// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Graphs();

// Create Document instance
Document doc = new Document();
// Add page to pages collection of PDF file
Page page = doc.Pages.Add();
// Create Graph instance
Aspose.Pdf.Drawing.Graph graph = new Aspose.Pdf.Drawing.Graph(100, 400);
// Add graph object to paragraphs collection of page instance
page.Paragraphs.Add(graph);
// Create Rectangle instance
Aspose.Pdf.Drawing.Rectangle rect = new Aspose.Pdf.Drawing.Rectangle(100, 100, 200, 120);
// Specify fill color for Graph object
rect.GraphInfo.FillColor = Aspose.Pdf.Color.Red;
// Add rectangle object to shapes collection of Graph object
graph.Shapes.Add(rect);
dataDir = dataDir + "CreateFilledRectangle_out.pdf";
// Save PDF file
doc.Save(dataDir);

在圖形對象中添加文本

Aspose.PDF支持在Graph對象內(nèi)添加文本。圖形對象的文本屬性提供了設(shè)置圖形對象文本的選項。以下代碼段顯示了如何在Rectangle對象內(nèi)添加文本。

// Open document
string outFile = "Graph.pdf";
Aspose.PDF.Document pdfDoc = new Aspose.PDF.Document();
Aspose.PDF.Page pdfPage = pdfDoc.Pages.Add();
Aspose.PDF.Drawing.Graph graph = new Aspose.PDF.Drawing.Graph(500, 100);
pdfPage.Paragraphs.Add(graph);
 
//Add rectangle with text
Aspose.PDF.Drawing.Rectangle rect = new Aspose.PDF.Drawing.Rectangle(0, 30, 50, 40);
rect.GraphInfo.LineWidth = 1f;
rect.GraphInfo.Color = Aspose.PDF.Color.Black;
rect.Text = new TextFragment("Rectangle");
graph.Shapes.Add(rect);
pdfDoc.Save(outFile);

將線對象添加到PDF

Aspose.PDF支持利用杠桿來添加Line對象，還可以在其中指定虛線元素，顏色和Line元素的其他格式。下面的代碼片段顯示了如何添加一個Rectangle充滿顏色的對象。

// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Graphs();

// Create Document instance
Document doc = new Document();
// Add page to pages collection of PDF file
Page page = doc.Pages.Add();
// Create Graph instance
Aspose.Pdf.Drawing.Graph graph = new Aspose.Pdf.Drawing.Graph(100, 400);
// Add graph object to paragraphs collection of page instance
page.Paragraphs.Add(graph);
// Create Rectangle instance
Aspose.Pdf.Drawing.Line line = new Aspose.Pdf.Drawing.Line(new float[] { 100, 100, 200, 100 });
// Specify fill color for Graph object
line.GraphInfo.DashArray = new int[] { 0, 1, 0 };
line.GraphInfo.DashPhase = 1;
// Add rectangle object to shapes collection of Graph object
graph.Shapes.Add(line);
dataDir = dataDir + "AddLineObject_out.pdf";
// Save PDF file
doc.Save(dataDir);

在頁面上畫線

Aspose.PDF支持線對象繪制從左下角到右上角以及從左上角到右下角的十字。請仔細閱讀以下代碼片段以實現(xiàn)此要求。

// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Graphs();

// Create Document instance
Document pDoc = new Document();
// Add page to pages collection of PDF document
Page pg = pDoc.Pages.Add();
// Set page margin on all sides as 0
pg.PageInfo.Margin.Left = pg.PageInfo.Margin.Right = pg.PageInfo.Margin.Bottom = pg.PageInfo.Margin.Top = 0;
// Create Graph object with Width and Height equal to page dimensions
Aspose.Pdf.Drawing.Graph graph = new Aspose.Pdf.Drawing.Graph((float)pg.PageInfo.Width , (float)pg.PageInfo.Height);
// Create first line object starting from Lower-Left to Top-Right corner of page
Aspose.Pdf.Drawing.Line line = new Aspose.Pdf.Drawing.Line(new float[] { (float)pg.Rect.LLX, 0, (float)pg.PageInfo.Width, (float)pg.Rect.URY });
// Add line to shapes collection of Graph object
graph.Shapes.Add(line);
// Draw line from Top-Left corner of page to Bottom-Right corner of page
Aspose.Pdf.Drawing.Line line2 = new Aspose.Pdf.Drawing.Line(new float[] { 0, (float)pg.Rect.URY, (float)pg.PageInfo.Width, (float)pg.Rect.LLX });
// Add line to shapes collection of Graph object
graph.Shapes.Add(line2);
// Add Graph object to paragraphs collection of page
pg.Paragraphs.Add(graph);

dataDir = dataDir + "DrawingLine_out.pdf";
// Save PDF file
pDoc.Save(dataDir);

使用Alpha顏色通道創(chuàng)建矩形

Aspose.PDF支持用某種顏色填充矩形對象。矩形對象也可以具有Alpha顏色通道以提供透明外觀。以下代碼段顯示了如何添加具有Alpha顏色通道的Rectangle對象。

// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Graphs();

// Instantiate Document instance
Document doc = new Document();
// Add page to pages collection of PDF file
Aspose.Pdf.Page page = doc.Pages.Add();
// Create Graph instance
Aspose.Pdf.Drawing.Graph canvas = new Aspose.Pdf.Drawing.Graph(100, 400);
// Create rectangle object with specific dimensions
Aspose.Pdf.Drawing.Rectangle rect = new Aspose.Pdf.Drawing.Rectangle(100, 100, 200, 100);
// Set graph fill color from System.Drawing.Color structure from a 32-bit ARGB value
rect.GraphInfo.FillColor = Aspose.Pdf.Color.FromRgb(System.Drawing.Color.FromArgb(128, System.Drawing.Color.FromArgb(12957183)));
// Add rectangle object to shapes collection of Graph instance
canvas.Shapes.Add(rect);

// Create second rectangle object
Aspose.Pdf.Drawing.Rectangle rect1 = new Aspose.Pdf.Drawing.Rectangle(200, 150, 200, 100);
rect1.GraphInfo.FillColor = Aspose.Pdf.Color.FromRgb(System.Drawing.Color.FromArgb(128, System.Drawing.Color.FromArgb(16118015)));
canvas.Shapes.Add(rect1);
// Add graph instance to paragraph collection of page object
page.Paragraphs.Add(canvas);

dataDir = dataDir + "CreateRectangleWithAlphaColor_out.pdf";
// Save PDF file
doc.Save(dataDir);

使用Alpha顏色通道創(chuàng)建矩形

創(chuàng)建矩形，圓形，Eclipse等圖形對象時，我們提供邊框的顏色信息以及填充顏色信息。為了具有透明的填充效果，可以使用Aspose.PDF.Color對象的FromArgb（..）方法。請查看以下代碼片段，該代碼片段演示了使用透明顏色填充矩形對象的功能。

// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Graphs();

int alpha = 10;
int green = 0;
int red = 100;
int blue = 0;
// Create Color object using Alpha RGB 
Aspose.Pdf.Color alphaColor = Aspose.Pdf.Color.FromArgb(alpha, red, green, blue); // Provide alpha channel
// Instantiate Document object
Document document = new Document();
// Add page to pages collection of PDF file
Page page = document.Pages.Add();
// Create Graph object with certain dimensions
Aspose.Pdf.Drawing.Graph graph = new Aspose.Pdf.Drawing.Graph(300, 400);
// Set border for Drawing object
graph.Border = (new Aspose.Pdf.BorderInfo(Aspose.Pdf.BorderSide.All, Aspose.Pdf.Color.Black));
// Add graph object to paragraphs collection of Page instance
page.Paragraphs.Add(graph);
// Create Rectangle object with certain dimensions
Aspose.Pdf.Drawing.Rectangle rectangle = new Aspose.Pdf.Drawing.Rectangle(0, 0, 100, 50);
// Create graphInfo object for Rectangle instance
Aspose.Pdf.GraphInfo graphInfo = rectangle.GraphInfo;
// Set color information for GraphInfo instance
graphInfo.Color = (Aspose.Pdf.Color.Red);
// Set fill color for GraphInfo
graphInfo.FillColor = (alphaColor);
// Add rectangle shape to shapes collection of graph object
graph.Shapes.Add(rectangle);
dataDir = dataDir + "AddDrawing_out.pdf";
// Save PDF file
document.Save(dataDir);

控制矩形的Z順序

在PDF文件中添加同一對象的多個實例時，我們可以通過指定Z順序來控制它們的呈現(xiàn)。當我們需要在彼此上方渲染對象時，也可以使用Z順序。下面的代碼片段顯示了將Rectangle對象彼此呈現(xiàn)的步驟。

// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Graphs();

// Instantiate Document class object
Document doc1 = new Document();
/// Add page to pages collection of PDF file
Aspose.Pdf.Page page1 = doc1.Pages.Add();
// Set size of PDF page
page1.SetPageSize(375, 300);
// Set left margin for page object as 0
page1.PageInfo.Margin.Left = 0;
// Set top margin of page object as 0
page1.PageInfo.Margin.Top = 0;
// Create a new rectangle with Color as Red, Z-Order as 0 and certain dimensions
AddRectangle(page1, 50, 40, 60, 40, Aspose.Pdf.Color.Red, 2);
// Create a new rectangle with Color as Blue, Z-Order as 0 and certain dimensions
AddRectangle(page1, 20, 20, 30, 30, Aspose.Pdf.Color.Blue, 1);
// Create a new rectangle with Color as Green, Z-Order as 0 and certain dimensions
AddRectangle(page1, 40, 40, 60, 30, Aspose.Pdf.Color.Green, 0);
dataDir = dataDir + "ControlRectangleZOrder_out.pdf";
// Save resultant PDF file
doc1.Save(dataDir);

private static void AddRectangle(Aspose.Pdf.Page page, float x, float y, float width, float height, Aspose.Pdf.Color color, int zindex)
{
    // Create graph object with dimensions same as specified for Rectangle object
    Aspose.Pdf.Drawing.Graph graph = new Aspose.Pdf.Drawing.Graph(width, height);
    // Can we change the position of graph instance
    graph.IsChangePosition = false;
    // Set Left coordinate position for Graph instance
    graph.Left = x;
    // Set Top coordinate position for Graph object
    graph.Top = y;
    // Add a rectangle inside the "graph"
    Aspose.Pdf.Drawing.Rectangle rect = new Aspose.Pdf.Drawing.Rectangle(0, 0, width, height);
    // Set rectangle fill color
    rect.GraphInfo.FillColor = color;
    // Color of graph object
    rect.GraphInfo.Color = color;
    // Add rectangle to shapes collection of graph instance
    graph.Shapes.Add(rect);
    // Set Z-Index for rectangle object
    graph.ZIndex = zindex;
    // Add graph to paragraphs collection of page object
    page.Paragraphs.Add(graph);
}

添加帶有漸變填充的圖形

Aspose.PDF支持創(chuàng)建純PDF文檔的功能，該文檔具有從一種專色/印刷色到另一種專色/印刷色的單一漸變。在下面的代碼示例中對此進行了說明。

// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Graphs();

// Instantiate Document class object
Document doc1 = new Document();
/// Add page to pages collection of PDF file
Aspose.Pdf.Page page1 = doc1.Pages.Add();
// Set size of PDF page
page1.SetPageSize(375, 300);
// Set left margin for page object as 0
page1.PageInfo.Margin.Left = 0;
// Set top margin of page object as 0
page1.PageInfo.Margin.Top = 0;
// Create a new rectangle with Color as Red, Z-Order as 0 and certain dimensions
AddRectangle(page1, 50, 40, 60, 40, Aspose.Pdf.Color.Red, 2);
// Create a new rectangle with Color as Blue, Z-Order as 0 and certain dimensions
AddRectangle(page1, 20, 20, 30, 30, Aspose.Pdf.Color.Blue, 1);
// Create a new rectangle with Color as Green, Z-Order as 0 and certain dimensions
AddRectangle(page1, 40, 40, 60, 30, Aspose.Pdf.Color.Green, 0);
dataDir = dataDir + "ControlRectangleZOrder_out.pdf";
// Save resultant PDF file
doc1.Save(dataDir);