父级形式的透明子窗体具有透明度和背景

Question

I have a form with background image and transparency key. In that form I put child form which must be fully transparent to show bakground of the parent form. If I set another transparency key to child form - it do not get transparency at all, and if i set transparency key of parent form - child cut through parent form's background image.

I need to use form - not user control so thats an issue. And i dont want to set dublicate background image to child form.

Im working visually. Here's code from designer:

1. That is my parent

     // // Main // this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F); this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font; this.BackColor = System.Drawing.Color.DarkRed; this.BackgroundImage = global::NWN_Tsuki.Properties.Resources.Book; this.BackgroundImageLayout = System.Windows.Forms.ImageLayout.None; this.ClientSize = new System.Drawing.Size(800, 665); this.Controls.Add(this.tableLayoutPanel1); this.Controls.Add(this.CloseBtn); this.DoubleBuffered = true; this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None; this.KeyPreview = true; this.MaximumSize = new System.Drawing.Size(800, 665); this.MinimumSize = new System.Drawing.Size(800, 665); this.Name = "Main"; this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen; this.Text = "Header"; this.TransparencyKey = System.Drawing.Color.DarkRed; this.KeyDown += new System.Windows.Forms.KeyEventHandler(this.Main_KeyDown); this.MouseDown += new System.Windows.Forms.MouseEventHandler(this.Main_MouseDown); this.tableLayoutPanel1.ResumeLayout(false); this.ResumeLayout(false); 

2. That is how I insert child into parent's panel:

     private void LeftPanel_Paint(object sender, PaintEventArgs e) { ToC toc = new ToC(); toc.TopLevel = false; toc.AutoScroll = true; this.LeftContent.Controls.Add(toc); toc.FormBorderStyle = FormBorderStyle.None; toc.Dock = DockStyle.Fill; toc.Show(); } 

3. Here is my Child:

     // // ToC // this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F); this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font; this.BackColor = System.Drawing.Color.Silver; this.ClientSize = new System.Drawing.Size(428, 396); this.Controls.Add(this.Ch7Btn); this.Controls.Add(this.Ch6Btn); this.Controls.Add(this.Ch5Btn); this.Controls.Add(this.Ch4Btn); this.Controls.Add(this.Ch3Btn); this.Controls.Add(this.Ch2Btn); this.Controls.Add(this.Ch1Btn); this.Controls.Add(this.label1); this.Name = "ToC"; this.Text = "ToC"; this.TransparencyKey = System.Drawing.Color.Silver; this.ResumeLayout(false); 

Thats the situation when child is Silver inside parent now matter that it has transparency key Silver. If i set this.BackColor = System.Drawing.Color.DarkRed; to Child - it will pierce parent's background.

Here's some images of what i mean.

Child with other then parent transparency key

Child with same as parent transparency

Answer 1

I am not sure why your child form's background is piercing the main form. There are two things you might try.

1. try setting both to a different color which your are most likely not going to use. Like Color.Magenta . (Altough I understand that you might have tried this already)

2. You should be able to set the Back color to transparent here

   Button1.BackColor = Color.Transparent;