1. Create a new square picture with the same length and width, such as 5*5 pixels, with a transparent background (the size of the picture determines the density of diagonal lines when filling behind).
2. Use the zoom tool to enlarge this picture to the maximum for easy operation. After zooming in, draw a diagonal line of the square with the selection of 1* 1 pixel and fill it with white. (The diagonal filling direction is consistent with the diagonal direction of the big picture filled behind, and the diagonal color is consistent with the diagonal of the big picture filled behind).
3. Press CTRL+A, select all squares with diagonal and transparent background, click the edit menu, select Save As Pattern and name it diagonal 1.
4. Open a large picture with diagonal lines, create a new layer, press CTRL+A to select all, click Edit menu, select Fill, select Use Pattern, click the pattern drop-down menu, and select Diagonal 1 just defined. The blending mode is normal and the opacity is 100%.
Basically, you're done. Hehe, you can adjust the transparency of the diagonal layer you just filled to make the pattern below clearer.